[2] Gonçalves, M., Makaryan, T., Papageorgiou, G., Herr, U. and Marti, O. (2011). Near-fields in Arrays of Triangular Particles: Coupling Effects and Field Enhancements. COMSOL Conference Stuttgart 2011, Stuttgart.
marti_221.pdf
Field enhancements are mainly due to surface plasmon resonances and near-field coupling between particles. High near-field enhancements can be exploited in surface enhanced Raman spectroscopy and other sensing methods. COMSOL Multiphysics was used to investigate coupling effects between noble metal particles. At inter-particle distances of few nanometers near-fields can be enhanced to values exceeding 100 under adequate polarization conditions. Red shifts in the near-field spectra occur in gold nanorods as the separation between particle decreases. Coupled trimmers of silver particles generate Fano-like resonances due to destructive interference between electric and magnetic dipoles.
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[3] Kleiner, A., Marti, O., Gotsmann, B., Knoll, A. and Dürig, U. (2011). "Topographic patterning by tribocharging of a polymer." Journal of Applied Physics 109: 124312.
marti_217.pdf  
A strong coupling between local charging and the specific volume of a polymer surface was exploited for topographic patterning. The charges were deposited locally using an Atomic Force Microscope (AFM) tip sliding over the surface at moderate bias voltages of up to 5 V. The same tip was used to measure both topography (using the AFM imaging mode) and charge (using the Kelvin Probe Force Microscopy method). The height of the obtained structures can reach several nanometers. With an estimated depth of the charge of 1 to 10 nm this corresponds to an increase of specific volume of 10 to 100 %. It is shown that the structures and the charges can be erased independently from each other. The charging is discussed in the context of molecular rearrangements necessary to store charge.
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[4] Gonçalves, M. R., Makaryan, T., Enderle, F., Wiedemann, S., Plettl, A., Marti, O. and Ziemann, P. (2011). "Plasmonic nanohole arrays fabricated using nanosphere-lithography, soft-lithography and plasma etching." Beilstein Journal of Nanotechnology 2: 448–458.
marti_216.pdf  
Cavities in metal films are usually fabricated by applying techniques based on electron-beam lithography or direct focused ion beam milling. These patterning methods are quite flexible in terms of shape tailoring, but are limited to small areas and are not adequate for parallel fabrication. To overcome this problem at least partly, fabrication methods related to nanosphere lithography has often been used allowing to obtain large scale arrays of nanostructures. Nanosphere lithography combined with electrochemical growth permits fabricating spherical cavities embedded in metal films. The confinement of surface plasmons in such cavities, excited by light, lead to plasmonic whispering gallery modes and near-field enhancements. We present two fabrication routes based on nanosphere lithography templates. One makes use of soft-lithography to obtain arrays of hemispheres of epoxy resin, which, in a second step, can be coated by metal films. The second uses the hexagonal array of triangular structures obtained by evaporation of a metal film on top of colloidal crystals as mask for reactive ion etching (RIE) of the substrate. In this way, the hexagonal pattern of the mask is transfered into the corresponding pattern of etched nanopillars. Combining such pillar arrays with methods allowing to invert the etching contrast, delivers ordered arrays of triangular holes within a metal film. Both fabrication methods demonstrate the preparation of large arrays of nanoholes within metal films at low cost. These structures can be used for strong localization of light due to their geometrical properties. Silver and gold films of different thicknesses were evaporated on top of hemispherical structures of epoxy resin of different radii and the reflectance was measured for optical wavelengths. An unexpected reduction of reflectivity for some bands and hemisphere sizes is observed in marked contrast to the behavior of metal coated polystyrene spheres.
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[5] Berger, N., Amirkhani, M., Abdelmohsen, M., Goncalves, M. R. and Marti, O. (2011). "The effect of different stabilizers on the formation of self-assembled porous film." Journal of Polymer Science: Polymer Physics 49(20): 1430–1436.
marti_215.pdf  
Breath-Figure (BF) technique produced highly ordered honeycomb structures by blowing an airflow across the surface of the end-functional polymer (polystyrene monocarboxy terminated) solution in a moist atmosphere, whereas the non-functional polymer (PS) solution could not produce any regular pattern. In the end-functional polymer solution water droplet is stabilized by the functional part of polymer, which has hydrophilic nature. The results show within an ordered area regularity of the pattern for three different solvents(toluene, chloroform and carbon disulfide) is same, whereas the size of the regular area is significantly larger for chloroform and carbon disulfide. Silica particles were also added to the both solutions of polystyrene monocarboxy terminated (PS-mCOOH) and linear polystyrene (PS) in order to find the effect of particles (as a different kind of stabilizer) on the pattern formation. Our study shows silica particles does not have any effect on the pattern formation of PSmCOOH films. However, while linear PS cannot produce any pattern through BF technique, mixing of the silica particles with PS solution results in regular patterns by decorating droplet with particles and preventing them from coalescing. It is also found that in PS/particle films just few decorated droplets were needed to produce a larger regular pattern. The size of bubble varies around 4% within a regular area for both systems, but it changes in the different area from 4.8 to 7 ìm for PS-mCOOH films and from 6 to 9 ìm for PS/particle films. Pores has spherical shape for PS-mCOOH films and flatten bottom for PS/Particles films however the volume of pores remain almost constant for both type of samples.
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[6] Kuznetsov, A. I., Evlyukhin, A. B., Gonçalves, M. R., Reinhardt, C., Koroleva, A., Arnedillo, M. L., Kiyan, R., Marti, O. and Chichkov, B. N. (2011). "Laser Fabrication of Large-Scale Nanoparticle Arrays for Sensing Applications." ACS Nano.
marti_214.pdf  
A novel method for high-speed fabrication of large scale periodic arrays of nanoparticles (diameters 40-200 nm) is developed. This method is based on a combination of nanosphere lithography and laser-induced transfer. Fabricated spherical nanoparticles are partially embedded into a polymer substrate. They are arranged into almost perfect hexagonal array and can be used for sensing applications. An optical sensor with the sensitivity of 365 nm/RIU and the figure of merit of 21.5 in the visible spectral range is demonstrated.
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[7] Sharifi, S., Amirkhani, M., Asla, J. M., Aliahmad, M. and Marti, O. (2011). "Collective Diffusion Coefficient of AOT Microemulsion." ISRN Materials Science accepted.
marti_213.pdf  
We study water-in-oil microemulsion (L2 phase) stabilized by AOT, dispersed in n-Decane at water/AOT molar ratio of 6.7. Collective diffusion coefficient (Dc) of microemulsion and microemulsion/Tetrabutylammonium-chloride (TBAC) systems were investigated by dynamic light scattering (DLS) technique. In the both systems at the constant water/AOT concentration the collective diffusion versus droplet mass fraction showed a linear relation with a negative slop. Furthermore, DLS experiment revealed that Dc of AOT/H2O/Decane microemulsions increased with added TBAC to the microemulsion. We also studied the structural information of pure AOT microemulsion by small angle X-ray scattering (SAXS) technique. The structural investigation of our samples did show that the increase of nonspherical droplets formation can explain the behavior of the Dc microemulsion. In addition, the structural investigation suggested that the formation of non-spherical droplets decrease with added TBAC.
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[8] Fischer, S., Men, Y., Diesner, T., Rieger, B. and Marti, O. (2011). "Toughening of Polypropylene at elevated temperatures by modifying the voiding properties via tie molecules." in preparation.
marti_212.pdf  
We reveal a simple self-reinforcing mechanism in polypropylene (PP) based on adding high molecular polypropylene to a typical grade. Using SAXS (Small-Angle X-Ray Scattering) to analyze the void formation process during deformation and tensile test to determine the mechanical behavior we show that the mechanical enhancement especially at elevated temperatures can be explained by the mechanism of tie molecules and their influence on the voiding during deformation. Additionally, we found that we can control the void size in uniaxially stretched polypropylene. Such an blending approach is of special importance regarding recycling properties.
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[9] Neues, F., Hild, S., Epple, M., Marti, O. and Ziegler, A. (2011). "Amorphous and crystalline calcium carbonate distribution in the tergite cuticle of moulting Porcellio scaber (Isopoda, Crustacea)." Journal of Structural Biology 175(1): 10-20.
marti_209.pdf  
The main mineral components of the isopod cuticle consists of crystalline magnesium calcite and amorphous calcium carbonate. During moulting isopods moult first the posterior and then the anterior half of the body. In terrestrial species calcium carbonate is subject to resorption, storage and recycling in order to retain significant fractions of the mineral during the moulting cycle. Composition and mineral distribution within the anterior and posterior tergite cuticle was studied for various moulting stages in Porcellio scaber. Synchrotron X-ray powder diffraction, elemental analysis and Raman spectroscopy indicate that amorphous calcium carbonate (ACC) is preferentially mobilized and stored probably due to its higher solubility compared to magnesium calcite. Deposition of ACC precedes the formation of calcite in distal layers of the cuticle.
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[10] Letsche, S., Pluntke, M., Tränkle, S., Gong, H., Marti, O., Jacobs, P., Mahlmann, D. M., Loosen, P. and Volkmer, D. (2011). "3D-Characterization of Microstructured Poly(methacrylic acid) Thin Films via Mach-Zehnder Interference Microscopy." Thin Solid Films 519(22): 8100-8108.
marti_208.pdf  
We demonstrate the adaption of a newly-developed Mach-Zehnder interference (MZI) microscope for the rapid 3D characterization of translucent microstructured polymer thin films. In order to quantify the accuracy of the Mach-Zehnder interferometer, comparative film thickness measurements of photolithographically patterned poly(methacrylic acid) polymer brushes are performed employing two alternative techniques: white light profilometry (WIM) and atomic force microscopy (AFM). When the refractive index of the polymer brushes is calculated from MZI data, we obtain a good agreement with results received from a reference ellipsometer. In contrast to surface probing techniques such as AFM or WIM, Mach-Zehnder interferometry is a transmitted light method that measures both surface height profiles and refractive index distributions. MZI thus enables the quantification of film homogeneity with respect to height and density variations at the lateral resolution of a refraction limited microscope. We conclude that MZI is an adequate tool for the rapid and non-destructive characterization of structured polymer thin films. This method should be particularly useful for production quality control of microstructured polymer thin films which possess great potential in electronic device fabrication and biotechnology.
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[11] Hoefling, M., Monti, S., Corni, S. and Gottschalk, K. E. (2011). "Interaction of β-Sheet Folds with a Gold Surface." PLoS ONE 6(6): e20925.

The adsorption of proteins on inorganic surfaces is of fundamental biological importance. Further, biomedical and nanotechnological applications increasingly use interfaces between inorganic material and polypeptides. Yet, the underlying adsorption mechanism of polypeptides on surfaces is not well understood and experimentally difficult to analyze. Therefore, we investigate here the interactions of polypeptides with a gold(111) surface using computational molecular dynamics (MD) simulations with a polarizable gold model in explicit water. Our focus in this paper is the investigation of the interaction of polypeptides with β-sheet folds. First, we concentrate on a β-sheet forming model peptide. Second, we investigate the interactions of two domains with high β-sheet content of the biologically important extracellular matrix protein fibronectin (FN). We find that adsorption occurs in a stepwise mechanism both for the model peptide and the protein. The positively charged amino acid Arg facilitates the initial contact formation between protein and gold surface. Our results suggest that an effective gold-binding surface patch is overall uncharged, but contains Arg for contact initiation. The polypeptides do not unfold on the gold surface within the simulation time. However, for the two FN domains, the relative domain-domain orientation changes. The observation of a very fast and strong adsorption indicates that in a biological matrix, no bare gold surfaces will be present. Hence, the bioactivity of gold surfaces (like bare gold nanoparticles) will critically depend on the history of particle administration and the proteins present during initial contact between gold and biological material. Further, gold particles may act as seeds for protein aggregation. Structural re-organization and protein aggregation are potentially of immunological importance Online Paper
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[12] Marti, O. (2010). Elektrizitätslehre - Skript zum Grundkurs 3 b für das Diplom Physik. Ulm, Ulm University
marti_211.pdf
Original: http://vts.uni-ulm.de/doc.asp?id=7491
Das Skript führt ein in die Elektrizitätslehre. Nach einer Diskussion der Elektrostatik wird mit einer relativistischen Betrachtung der Magnetismus eingeführt. Mit den Maxwellgleichungen werden elektromagnetische Wellen erklärt.
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[13] Fischer, S., Marti, O., Diesner, T. and Rieger, B. (2010). "Small-Angle X-ray Scattering on Melt-Spun Polypropylene Fibers: Modeling and Data Reduction." Macromolecules 43(11): 5009–5015.
marti_207.pdf  
We present a method for the evaluation of SAXS data of highly oriented semicrystalline polymers, allowing us to determine up to seven structural parameters from the measurements. The utilized samples were polypropylenes with varied distributions of the molecular weight, which were spun with different take-up velocities to alter the spinline stress, thus influencing the structural properties. We were able to determine the degree of orientation, lamella radius, long spacing, lattice distortion, and lamella height simultaneously. The microscopic orientation was compared with the crystalline orientation evaluated by Herman’s orientation function from WAXS.
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[14] Zhang, F. Z., Walheim, S., Schimmel, T. and Marti, O. (2010). "New laser apparatus to measure oscillation amplitude down to picometer at megahertz frequencies." Review of Scientific Instruments 81(3): 035116-035116-4.
marti_206.pdf  
A laser setup to study shear oscillations at small amplitudes with resonance frequencies up to 3 MHz is presented. The new approach combines gauging of the Gaussian laser beam and a lock-in amplifier. The device is tested with a 3 MHz AT-cut quartz crystal. The oscillation amplitude at the edge of the electrode on the quartz crystal is measured with a resolution of 2 pm.
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[15] Marti, O. and Hübner, K. (2010). Force Measurements with Optical Tweezers. Nanotechnology Handbook. B. Bhushan: in proof.
marti_204.pdf

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[16] Fischer, S., Diesner, T., Rieger, B. and Marti, O. (2010). "Simulating and evaluating small-angle X-ray scattering of micro-voids in polypropylene during mechanical deformation." Applied Crystallography 43: 603-610.
marti_203.pdf  
Micro-voids which evolve during mechanical deformation in polypropylene have been characterized by small-angle X-ray scattering (SAXS). Such voids can be modelled as randomly distributed cylinders which are oriented along the stretching direction, showing a log-normal size distribution. The model and simulation results are presented here. Advantages and disadvantages of our approach, the validity of the model and important considerations for data evaluation are discussed. Data analysis of two-dimensional scattering images has been performed using a fully automated MATLAB routine by direct model fitting to scattering images.
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[17] Gong, H., Pluntke, M., Marti, O., Walther, P., Gower, L., Cölfen, H. and Volkmer, D. (2010). "Multilayered CaCO3/Block-Copolymer Materials via Amorphous Precursor to Crystal Transformation." Colloids and Surfaces A: Physicochemical and Engineering Aspects 354: 279-283.
marti_201.pdf  
Nacre-type organic/inorganic hybrid multilayers can be fabricated through a continuous polymerinduced liquid precursor (PILP) layer formed underneath a poly(styrene)-block-poly(acrylic acid) (PS-b-PAA) block copolymer monolayer. Subsequent Layer-by-Layer transfer of block copolymer/PILP films leads to a multilayer with organic-inorganic hybrid architecture. The subsequent annealing process transforms the PILP layers into layers of polycrystalline CaCO3, which morphologically resemble that of biogenic nacre.
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[18] Marti, O. (2010). Wärmelehre, Schwingungen und Elastomechanik: Skript zu Grundlagen II der Physik. Ulm, Ulm University
marti_199.pdf
Original: http://vts.uni-ulm.de/doc.asp?id=7482
Einführung in die Experimentalphysik für das 2. Semester Diplom Physik: Behandelt werden Schwingungen und eindimensionale Wellen, die Mechanik deformierbarer Medien und die Wärmelehre. Das Skript hat neben einem Abbildungsverzeichnis auch ein Stichwortverzeichnis und einen Anhang über mathematische Methoden.
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[19] Marti, O. (2010). Vorlesungsskript PHYS1100 Grundlagen der Physik I für Physiker, Wirtschaftsphysiker und Lehramtskandidaten. Ulm, Ulm University. 1
marti_198.pdf
Original: http://vts.uni-ulm.de/docs/2010/7263/vts_7263_10265.pdf
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[20] Lehn, R. and Marti, O. (2010). Messen von Distanzen mit Licht - Wege in die Nanowelt. Ulm, Ulm University
marti_188.pdf
Original: http://vts.uni-ulm.de/doc.asp?id=7331
Eine Zusammenfassung der Optik, die relevant für die Messung von Distanzen im Mikrometer- und Nanometerbereich ist.
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[21] Kreyes, A., Amirkhani, M., Lieberwirth, I., Mauer, R., Laquai, F., Landfester, K. and Ziener, U. (2010). "The Longest beta-Unsubstituted Oligothiophenes and Their Self-Assembly in Solution." Chem. Mater..
amirkhani_2010.pdf  
beta-Unsubstituted oligothiophenes with up to 13 thiophene units are described. These represent the longest oligomers ever reported in this class. In solution, those compounds show a temperature- and concentration-dependent aggregation behavior. Absorption, fluorescence, dynamic light scattering, and cryo-transmission electron microscopy investigations reveal the formation of wormlike aggregates several hundred nanometers in length and ca. 5 nm in width.
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[22] Hild, S., Neues, F., Znidaršiè, N., Štrus, J., Epple, M., Marti, O. and Ziegler, A. (2009). "Ultrastructure and mineral distribution in the tergal cuticle of the terrestrial isopod Titanethes albus. Adaptations to a karst cave biotope." Journal of Structural Biology 168: 426–436.
marti_202.pdf  
Composition and spatial distribution of organic and inorganic materials within the cuticle of isopods vary between species. These variations are related to the behaviour and habitat of the animal. The troglobiotic isopod Titanethes albus lives in the complete darkness of caves in the Slovenian Karst. This habitat provides constant temperature and saturated humidity throughout the year and inconsistent food supply. These conditions should have lead to functional adaptations of arthropod cuticles. However, studies on structure and composition of cave arthropod cuticles are rare and lacking for terrestrial isopods. We therefore analysed the tergite cuticle of Titanethes albus using transmission and field emission electron microscopy, confocal ì-Raman spectroscopic imaging, quantitative X-ray diffractometry, thermogravimetric analysis and atomic absorption spectroscopy. The ultrastructure of the epicuticle suggests a poor resistance against water loss. A weak interconnection between the organic and mineral phase within the endo- and exocuticle, a comparatively thin apical calcite layer, and almost lack of magnesium within the calcite crystal lattice suggest that the mechanical strength of the cuticle is low in the cave isopod. This may possibly be of advantage in maintaining high cuticle flexibility and reducing metabolic expenditures.
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[23] Letsche, S. A., Steinbach, A. M., Pluntke, M., Marti, O., Ignatius, A. and Volkmer, D. (2009). "Usage of polymer brushes as substrates of bone cells." Frontiers of Materials Science in China 3(2): 132-144.
marti_200.pdf  
Abstract Implant medical research and tissue engineering both target the design of novel biomaterials for the improvement of human health and clinical applications. In order to develop improved surface coatings for hard tissue (bone) replacement materials and implant devices, we are developing micropatterned coatings consisting of polymer brushes. These are used as organic templates for the mineralization of calcium phosphate in order to improve adhesion of bone cells. First, we give a short account of the current state-of-the-art in this particular field of biomaterial development, while in the second part the preliminary results of cell culture experiments are presented, in which the biocompatibility of polymer brushes are tested on human mesenchymal stem cells.
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[24] Schimmel, T. and Marti, O. (2009). Lubrication by Exposing to Light. Pub. No.: US 2008/0312109 A1. United States of America, Landesstiftung Baden-Württemberg GmbH, Stuttgart (DE)marti_197.pdf
The present invention concerns a method for a location and/or time-dependent alteration of the friction coefficient and/or adhesion force between two bodies, which includes irradiation of one or both contact surfaces between the bodies with radiation, use of the method according to the invention for location and/or time-dependent alteration of the friction coefficient and/or adhesion force between to bodies, a system that includes two bodies in which the friction coefficient and/or the adhesion force between the bodies can be temporarily or permanently altered, and a device for location and/or time-dependent regulation of the friction coefficient and/or adhesion force which includes the system according to the invention and a control unit.
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[25] Boger, A., Imhof, C., B.Heise, Marti, O., C.Troll, Rieger, B. and S.Hild (2009). "Stress induced changes in microstructure of a low crystalline Polypropylene investigated at uniaxial stretching." Journal of Applied Polymer Science 112(1): 188-199.
marti_192.pdf  
Novel asymmetric metallocene catalysts lead to low isotactic polypropylenes (iPP) with randomly distributed stereo irregularities. The polypropylenes are low crystalline and show elastic mechanical behaviour due to physical cross linking. The morphology of such iPP, responsible for mechanical properties observed is still sparsely resolved. In the present work a low isotactic, low crystalline metallocene iPP containing randomly distributed stereoerreors was investigated. The influence of the chain microstructure in the elastic properties was studied using two complementary investigation methods, X-ray diffraction and scanning force microscopy. This includes the efforts to come closer to the main question of the nature of the physical cross-links, as reason for the high elastic behavior. For a better understanding of the unique mechanical properties microscopic changes in morphology and strain induced variation in chain orientation were monitored during uniaxially stretching using scanning force microscopy (SFM) and wide angle x-ray scattering (WAXS) measurements. For quantitative analysis and discussion the polymer chain orientations were calculated. The correlation between the orientation, the arrangements of the amorphous and crystalline phases observed by SFM and the mechanical properties of the material at different elongation ratios allows an interpretation of the macroscopic behavior on the microscopic scale. Interpretation are confirm with existing structural models, which proposed that small crystalline domains act as physical cross-links for the amorphous matrix.
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[26] Amirkhani, M., Gorini, G. and Leporini, D. (2009). "Second harmonic generation studies of intrinsic and extrinsic relaxation dynamics in poly(methy1 methacrylate)." Journal of Non-Crystalline Solids 355(34-36): 1707-1712.
amirkhani_002.pdf  
Second harmonic generation (SHG) is used to monitor the reorientation a dopant chromophore in slightly entangled poly(methy1 methacrylate) (PMMA). The effect of charge and temperature on both the decay and the much less studied onset modes of SHG signal at temperatures above the glass transition has been examined. At variance with the theoretical predictions, it is shown that the onset and the decay times are not coincident. An isothermal experiment above the glass transition shows a lengthening of relaxation time of the decay mode due to successive poling process, which is ascribed to charge memory effects. In contrast, the latter do not affect the onset characteristic time. The effect of temperature above the glass transition on dopant rotation and polymer relaxations has been also examined. As temperature increases the relaxation times of both the onset and the decay modes decrease. If the surface charge and the charge memory effect are erased, the decay time compares quite well with the structural relaxation time. Differently, the onset time exhibits a partial decoupling. © 2009 Elsevier B.V. All rights reserved.
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[27] Letsche, S., Steinbach, A., Pluntke, M., Marti, O., Ignatius, A. and Volkmer, D. (2008). Applications of patterned Polymer Brushes as Substrate of Bone Cells. Biomineralization: from Paleontology to Materials Science. J. L. Arias and M. S. Fernández. Santiago, Chile.
marti_205.pdf

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[28] Marti, O. and Schimmel, T. (2008). Application of Nanostructured Surfaces for Immobilization of Oligomers - Investigation of the Resulting Dynamics by Means of Scanning Probe Microscopy. Nanotechnology, Physics, Chemistry and Biology of Functional Nanostructures. T. Schimmel, H. v. Löhneysen, C. Obermair and M. Barczewski. Stuttgart, Landesstiftung Baden-Württemberg: 317-343.
marti_196.pdf
Friction is an everyday physical phenomenon. Even on the smallest scale, parts are sliding over or sticking to each other. A tool that can access the nanoscale is the Atomic Force Microscope (AFM). With this device, it is possible to mimic the dynamics of a small probe slid-ing atop of a sample surface experimentally. Usually, relative veloci-ties in the range of micrometers per second can be achieved by scan-ning across the surface. However, much higher velocities occur in technical reality, e.g. the I/O-head of a hard disk or the valves in an engine move at several meters per second relative to their counter-parts. This gap of several orders of magnitude can be closed by oscil-lating the sample relative to the probe at very high frequencies and small amplitudes. This is known as Dynamic Friction Force Micros-copy (DFFM). Therefore, a high frequency-AFM setup has been de-veloped in the Dept. of Experimental Physics in Ulm. For first experi-ments with this kind of microscope, chemically produced lateral struc-tures on surfaces, which reveal high frictional contrast while being flat, are of utmost interest. As an ideal match, these ultra-flat samples were found in the Karlsruhe group (Applied Physics/UniKA and Insti-tute for Nano-Technology/FZK). These samples show pure oxidic areas and regions that are covered by alkane monolayers of silanes. These have negligible topography (one to two nanometers), while revealing a strong contrast in their mechanical behavior. Especially their frictional behavior is technologically interesting, since these can be used as ultra-thin lubricants. An AFM technique that has proven to be suitable to thin polymeric layers is the Digital Pulsed Force Mode (DPFM). At a fairly high repetition rate (some kHz) the sample is probed upon its mechanical properties. With this tool a new grade of insight has been gained into the nanomechanics of such surfaces regarding elastic as well as viscoelastic behavior. First, the formation of a point-contact had to be understood before investigating frictional properties. Therefore, a measurement guideline has been developed allowing reliable and reproducible AFM measurements and experi-ments have been conducted on samples of polymer-mixtures on sili-con and glass substrates as well as thiol and silane monolayers. The contact mechanical analysis is based on a JKR-like model [1]. Fric-tion velocities of approximately one meter per second have been reached applying a new excitation and signal detection setup. As these measurements just recently became available, the results are not yet totally understood. It was possible to bridge the gap in relative velocity, to allow future theoretical analysis to be substantiated with our experimental results.
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[29] Marti, O. (2008). Buchbesprechung: "Big Business und Big Bang. Berufsund Studienführer Physik, M. Rauner, S.]orda." Physik in unserer Zeit. 39: 255
marti_195.pdf

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[30] Schimmel, T. and Marti, O. (2008). Verfahren zur kontrollierten Beeinflussung von Reibung (Photolubrikation)To top

[31] Bunk, O., Dierolf, M., Kynde, S., Johnson, I., Marti, O. and Pfeiffer, F. (2008). "Influence of the overlap parameter on the convergence of the ptychographical iterative engine." Ultramicroscopy 108: 481–487.
marti_189.pdf  
The ptychographical iterative engine (PIE) algorithm is examined with both simulated and experimental scanning coherent-diffraction microscopy data. The optimum overlap in terms of image quality, dose on the sample and time of measurements is determined using simulated diffraction data. The validity of the results is supported by experimental helium–neon laser light diffraction data.
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[32] Gonçalves, M. R., Siegel, A. and Marti, O. (2008). "SERS observed in periodic metallo-dielectric nanostructures fabricated using coated colloidal crystals." SPIE - The International Society for Optical Engineering. Proceedings of the SPIE - The International Society for Optical Engineering 6988: 698809-1-12.
marti_187.pdf  
Surface enhanced Raman scattering (SERS) has been investigated for different molecules adsorbed on metallic nanostructures. The local field enhancements due to the confinement and resonances of surface plasmons, can reach many orders of magnitude. These field enhancements allow molecules to produce strong Raman spectra, although they have tiny Raman scattering cross sections. The high sensitivity demonstrated was relevant for sensing applications of single molecules. We have investigated experimentally the SERS effect on rhodamine 6G molecules, adsorbed on triangular silver particles and photonic metallo-dielectric structures based on polymers. These structures were fabricated by evaporation of a thin metallic film on colloidal crystals followed by casting in PDMS and epoxy resin. In the later, the polystyrene spheres were removed by sonication in organic solvents. The remaining structure allows molecules to be adsorbed at its metallic surface, on top of the triangular particles or inside the spherical holes. The SERS spectra were measured by a scanning confocal Raman microscope. The location of the SERS active centers (hot spots) in arrays of triangular particles (corners and edges) is correlated with the optical near-field enhancements obtained by numerical simulations. In metallo-dielectric photonic structures made of PDMS the Raman images show regions of stable SERS spectra (several pixels wide) and many isolated bright pixels.The isolated pixels are instable in time, i.e. show spectral blinking. The photonic structures we propose can be fabricated in a reproducible way. The field enhancements depend mainly on the size and shape of the arrays, which is not the case for etched silver films and for clusters prepared by colloidal silver. Thus, they are more suitable to investigate the electromagnetic contribution to SERS. (22 References).
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[33] Marti, O., Holzwarth, M. and Beil, M. (2008). "Measuring Nanomechanical Properties of Cancer Cells by Digital Pulsed Force Mode Imaging." Nanotechnology 19: 384015 (7pp).
marti_186.pdf  
In this paper, we demonstrate that the digital pulsed force mode data can distinguish two cancer cell lines (HeLa, Panc) by their mechanical properties. The live cells were imaged in buffer solution. The digital pulsed force mode measured 175 force-distance-curves per second, which, due to the speed of the measurement, were distorted by the viscous drag in the buffer. We show that this drag force causes a sinusoidal addition to the force-distance-curves. By subtracting the viscous drag effect one obtains standard force-distance-curves. The force-distance-curves are then evaluated to extract key data on the curves, such as adhesion energies, local stiffness or the width of the hysteresis loop. These data are then correlated to classify the force-distance-curves. We show examples based on the width of the hysteresis loop and the adhesion energies. Outliers in this classification scheme are points where, potentially, interesting new physics or different physics might happen. Based on classification schemes adapted to experimental settings, we propose that the digital pulsed force mode is a tool to evaluate the time evolution of the mechanical response of cells.
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[34] Dierolf, M., Bunk, O., Kynde, S., Thibault, P., Johnson, I., Menzel, A., Jefimovs, K., David, C., Marti, O. and Pfeiffer, F. (2008). "Ptychography & Lensless X-Ray Imaging." European Physics News 39(1): 22-24.
marti_185.pdf  
If an object is illuminated with coherent electromagnetic radiation, e.g., by visible laser light or highly brilliant x-rays, a diffraction pattern is formed in the Fraunhofer far field that is related via a Fourier transform to the optical transmission function of the object. The aim of coherent diffractive imaging (CDI), or so-called lensless imaging, is to directly reconstruct the original optical transmission function of the specimen from its measured diffraction pattern.
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[35] Hild, S., Marti, O. and Ziegler, A. (2008). "Spatial distribution of calcite and amorphous calcium carbonate in the cuticle of the terrestrial crustaceans Porcellio scaber and Armadillidium vulgare." Journal of Structural Biology 163(1): 100-108.
marti_184.pdf  
The crustacean cuticle is an interesting model to study the properties of mineralized biocomposites. The cuticle consists of an organic matrix composed of chitin-protein fibers associated with various amounts of crystalline and amorphous calcium carbonate. It is thought that in isopods the relative amounts of these mineral modifications depend on its function and the habitat of the animal. Besides the composition the distribution of the various components should affect the properties of the cuticle. However, the spatial distribution of calcium carbonate modifications within the crustacean cuticle is unknown. Therefore, we analyzed the mineralized cuticles of the terrestrial isopods Armadillidium vulgare and Porcellio scaber using scanning electron-microscopy, electron probe microanalysis and confocal ì-Raman spectroscopic imaging. We show for the first time that the mineral phases are arranged in distinct layers. Calcite is restricted to the outer layer of the cuticle that corresponds to the exocuticle. Amorphous calcium carbonate is located within the endocutile that lies below the exocuticle. Within both layers mineral is arranged in rows of granules with diameters of about 20 nm. The results suggest functional implications of mineral distribution that accord to the moulting and escape behaviour of the animals.
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[36] Hinz, M., Marti, O., Gotsmann, B., Lantz, M. A. and Dürig, U. (2008). "High resolution vacuum scanning thermal microscopy of HfO2 and SiO2." Applied Physics Letters 92: 043122.
marti_183.pdf  
We present scanning thermal microscopy (SThM) measurements on a sample consisting of regions of 3nm thick HfO2 film and 2nm thick SiO2 on a silicon substrate. The experiments were preformed in high vacuum conditions using microfabricated cantilvers with sharp heatable tips, facilitating the unprecedented achievement of a lateral SThM image resolution of 25 nm. In addition, the heat transfer through the tip to the sample was investigated using approach curves and used to determine the thermal conductivity of the 3nm thick HfO2 layer.
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[37] Gigler, A. M. and Marti, O. (2008). Quantitative measurement of materials properties with the (Digital) Pulsed Force Mode. Applied Scanning Probe Methods IX - Characterization. B. Bhushan, H. Fuchs and M. Tomitori. Berlin Heidelberg, Springer Verlag. XI: 23-54.
marti_180.pdf
In this contribution we present the potential of digital pulsed force mode (DPFM) atomic force microscopy (AFM) for mapping the local mechanical properties to surface topology. In the first part, we review the pulsed force mode principles and compare this mode with other common modes of dynamic AFM operation. Then, we present an overview of the different model for tip-sample interaction based on continuum mechanics theories. In a general view, we then show how the huge amount of data that is acquired during DPFM imaging is stored and how it can be processed in order to provide insight into local mechanics of the sample surfaces. Applications of this measurement technique show the possible impact of DPFM on condensed soft matter samples as well as possible extensions towards measurements of the in-plane mechanics of the tip and the surface. All mechanical DPFM data were analyzed on the basis of continuum mechanical models. We conclude our contribution with an overview of this technique and its benefits for lateral compositional mapping.
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[38] Gonçalves, M. R., Siegel, A. and Marti, O. (2008). "Influence of the light scattering form factor on the Bragg diffraction patterns of arrays of metallic nanoparticles." Journal of Microscopy 229(3): 475-482.
marti_166.pdf  
Accurate models for the light scattering form factors of nanoparticles are of crucial importance to characterise their light scattering and to develop new photonic devices based on arrays of particles. For highly symmetrical shapes analytical or semi-empirical models exist. For complex shapes no global model is known, though the angular spectrum of scattering for specific particle shapes is possible to obtain by numerical simulations. In order to check the validity of the models of scattering form factors, we present a experimental setup capable of measuring Bragg diffraction patterns of arrays of nanoparticles and other nanostructures, in the visible and short infra-red regions of the spectrum. Confocal measurements of the scattered light of hexagonal arrays of triangular nanoparticles showed strong dependencies on the material of the particles and on their shape. This dependency has been confirmed by the diffraction experiments. The experimental setup presented, with some technical modifications, allows one to map directly the surface plasmon-polaritons dispersion relation of the array of particles or nanostructures of lattice constants between 0.4 and 3 µm.
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[39] Csete, M., Sipos, A., Szalai, A., Mathesz, A., Deli, M. A., Veszelka, S., Schmatulla, A., Kohazi-Kis, A., Osvay, K., Marti, O. and Bor, Z. (2007). "Bio-sensing based on plasmon-coupling caused by rotated sub-micrometer gratings in metal-dielectric interfacial layers." SPIE - The International Society for Optical Engineering. Proceedings of the SPIE - The International Society for Optical Engineering 6755(1): 67550X-1-13.

Novel plasmonic sensor chips are prepared by generating sub-micrometer periodic patterns in the interfacial layers of bimetal-polymer films via master-grating based interference method. Poly-carbonate films spin-coated onto vacuum evaporated silver-gold bimetallic layers are irradiated by the two interfering UV beams of a Nd:YAG laser. It is proven by pulsed force mode AFM that periodic adhesion pattern corresponds to the surface relief gratings, consisting of sub-micrometer droplet arrays and continuous polymer stripes, induced by p- and s-polarized beams, respectively. The characteristic periods are the same, but more complex and larger amplitude adhesion modulation is detectable on the droplet arrays. The polar and azimuthal angle dependence of the resonance characteristic of plasmons is studied by combining the prism- and grating-coupling methods in a modified Kretschmann arrangement, illuminating the structured metal-polymer interface by a frequency doubled Nd:YAG laser through a semi-cylinder. It is proven that the grating-coupling results in double-peaked plasmon resonance curves on both of the droplet arrays and line gratings, when the grooves are rotated to an appropriate azimuthal angle, and the modulation amplitude of the structure is sufficiently large. Streptavidin seeding is performed to demonstrate that small amount of protein can be detected monitoring the shift of the secondary resonance minima. The available high concentration sensitivity is explained by the promotion of protein adherence in the structure's valleys due to the enhanced adhesion. The line-shaped polymer gratings resulting in narrow resonance peaks are utilized to demonstrate the effect of therapeutic molecules on Amyloid-beta peptide, a pathogenic factor in Alzheimer disease. (21 References).
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[40] Meinhard, D., Wegner, M., Kipiani, G., Hearley, A., Reuter, P., Fischer, S., Marti, O. and Rieger, B. (2007). "New Nickel(II) Diimine Complexes and the Control of Polyethylene Microstructure by Catalyst Design." Journal of the Americal Chemical Society 129: 9182-9191.
marti_182.pdf  
Starting from differently substituted boronic acids as versatile building block, new “ortho-aryl” R-diimine ligands a-h were synthesized in an easy, high-yielding route. Reaction of the complex precursor diacetylacetonato-nickel(II) with a trityl salt, like [CPh3] [B(C6F5)4] or [CPh3] [SbCl6], in the presence of the diimine ligands afford the monocationic, square planar complexes 2a-g in almost quantitative yields. Suitable crystals (2d¢,e,f,g) were submitted for X-ray diffraction analysis. A geometry model was developed to describe the orientation of ligand fragments around the nickel(II) center that influence the polymer microstructure. At elevated reaction temperature and pressure, and in the presence of hydrogen, 2a-e catalyze the homopolymerization of ethylene to give branched PE products ranging from HD- to LLD-PE grades. The polymerization results indicate the possibility of precise microstructure control depending on the particular complex substitution. Preliminary investigations on material density and mechanical behavior by uniaxial stretching until failure point toward new material properties that can result from the simple ethylene monomer by catalyst design.
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[41] Csete, M., Sipos, Á., Szalai, A., Szekeres, G., Mathesz, A., Csákó, T., Osvay, K., Bor, Z., Deli, M. A., Veszelka, S., Schmatulla, A. and Marti, O. (2007). "Comparative study of sub-micrometer polymeric structures: dot-arrays, linear and crossed gratings generated by UV laser based two-beam interference, as surfaces for SPR and AFM based bio-sensing." Applied Surface Science 254(4): 1194-1205.
marti_181.pdf  
Two-dimensional gratings are generated on the surface of Poly-Carbonate films spin-coated onto thin Au-Ag bimetallic layers by two-beam interference technique. Sub-micrometer periodic polymer dots and stripes are induced illuminating the PC surface by p- and spolarized beams of a frequency quadrupled Nd:YAG laser, and crossed gratings are prepared by rotating the substrates between two sequential treatments. It is shown by pulsed force mode AFM that the mean value of the adhesion modulation is enhanced on the dot-arrays and on the crossed gratings. The grating coupling results in double peaks on the angle dependent resonance curves of surface plasmons, excited on rotated two-dimensional structures by frequency doubled Nd:YAG laser. The comparison of the resonance curves proves, that a surface profile ensuring minimal undirected scattering is required to optimize the coupling on the periodic objects, in addition to the modulation amplitude larger than a minimal value, and to the orientation matching an optimal azimutal angle. The secondary minima are the narrowest in presence of linear gratings on multi-layers having optimized composition, and on crossed structures consisting of two sets of appropriately oriented polymer stripes. The high coupling efficiency is accompanied by the high detection sensitivity on crossed gratings. The rotated-crossed grating coupled SPR and the chemical heterogeneity sensitive tapping-mode AFM are utilized to realize bio-sensing, and to investigate the interaction of Amyloid-beta peptide, a pathogenetic factor in Alzheimer disease, with therapeutical molecules.
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[42] Csete, M., Khazi-Kis, A., Megyesi, V., Osvay, K., Bor, Z., Pietralla, M. and Marti, O. (2007). "Coupled surface plasmon resonance on bimetallic films covered by sub-micrometer polymer gratings." Organic Electronics 8(2-3): 148-60.

Angular interrogation investigation of the rotated grating-coupled surface plasmon resonance was performed, via exciting plasmons on special sensing layers by a frequency doubled continuous Nd:Yag laser beam in Kretschmann arrangement. NBK7 glass substrates were evaporated by silver and gold layers having appropriate thicknesses to ensure a narrow plasmon resonance peak. Thin poly-carbonate films spin-coated onto the bimetallic layers were patterned by the fourth harmonic of a pulsed mode Nd:Yag laser applying a master grating-based interference method. The pulsed force mode atomic force microscopic investigation has shown the existence of a surface relief grating and a coexistent adhesion modulation having a period of 416nm. The conditions of the grating-coupling effect were determined for shallow sub-micrometer polymer gratings, and secondary minima were detected on the resonance curves measured in presence of polymer patterns, according to the calculations. The indispensability of a minimal modulation amplitude and the existence of an optimal rotation angle of the grating grooves with respect to the plasmon propagation direction were experimentally proven. The position of the emerged secondary resonance minimum indicated that the average film thickness was decreased caused by material removal during the structure formation. It was shown by tapping-mode AFM that the sub-micrometer adhesion modulation resulted in periodic adherence of streptavidin in the structure's valleys. The attachment of a small amount of protein was detected based on the shift of the secondary resonance peak. The capability of the polymer grating for sensitivity enhancement was demonstrated, proving that the secondary peak shift is highly sensitive to the protein concentration. The application of the polymer grating covered bimetallic films as transducing layers in novel bio-sensorization method based on rotated grating coupling is proposed. [All rights reserved Elsevier]. (24 References).
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[43] Bhushan, B. and Marti, O. (2007). Scanning probe microscopy - principle of operation, instrumentation, and probes. Springer Handbook of Nanotechnology. B. Bhushan. New York, Springer: 591-635.
marti_176.pdf
Since the introduction of the STM in 1981 and the AFM in 1985, many variations of probe-based microscopies, referred to as SPMs, have been developed. While the pure imaging capabilities of SPM techniques initially dominated applications of these methods, the physics of probe-sample interactions and quant. analyses of tribol., electronic, magnetic, biol., and chem. surfaces using SPMs have become of increasing interest in recent years. SPMs are often assocd. with nanoscale science and technol., since they allow investigation and manipulation of surfaces down to the at. scale. As our understanding of the underlying interaction mechanisms has grown, SPMs have increasingly found application in many fields beyond basic research fields. In addn., various derivs. of all these methods have been developed for special applications, some of them intended for areas other than microscopy. This chapter presents an overview of STM and AFM and various probes (tips) used in these instruments, followed by details on AFM instrumentation and analyses
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[44] Siegel, A., Gonçalves, M. R., Ameling, R. and Marti, O. (2007). "Investigations of the light scattering form factor of metallic nanostructures using Bragg diffraction." Journal of Optics A 9: S443-S449.
marti_172.pdf  
The scattering of light by metallic nanostructures is one of key phenomena to understand how the light couples to surface plasmons. The local field enhancement and the surface plasmon resonances are two other associated effects of special importance for surface enhanced Raman scattering. The size, shape and material of the structures determine the light scattering efficiency at its angular spectrum, in a very complex way. Only simple shapes have been reasonably well modelled so far. Therefore, a measurement of the scattering properties of complex structures, by dierent illumination conditions, is fundamental to test scattering models. Using an approach analogue to X-ray diffraction, we investigate the light scattering of arrays of identical nanoparticles and can test the validity of the models of light scattering form factors. Arrays of particles of different size, shape and lattice constants were investigated this way. It was observed that the shape of the particles and its material have a strong influence of the distribution of intensities of the Bragg diffraction patterns. In addition to that, we have build an experimental setup to measure the dispersion relation of arrays of nanoparticles, or two-dimensional gratings, using total internal illumination.
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[45] Gonçalves, M. R., Siegel, A., Ameling, R. and Marti, O. (2007). Scattering of light at micro- and nanostructures of triangular shape. Photonics West 2007, Complex Light and Optical Forces, San Jose, USA, SPIE.
marti_171.pdf
The development of new photonic and plasmonic devices rely on the new pioneering techniques of micro- and nanofabrication, combining both standard lithography techniques and self-assembly. The combination of colloidal crystals, projection patterning and soft-lithography are examples of fabrication techniques which allow to obtain complex structures of sizes smaller than the wavelength of visible light. In many cases, the structures fabricated by this way are not possible to obtain using standard lithography techniques, like electron-beam, UV-VIS lithography and focused ion beam (FIB). We have used two-dimensional colloidal crystals as templates to fabricate arrays of isolated metallic particles of triangular shape on surfaces and two-dimensional gratings. Either dielectric or metallic structures can be obtained. In the later case the coupling between light and the locally confined surface plasmon-polaritons leads to resonances, field enhancements and other related phenomena. The scattering properties of the particles and gratings have been investigated experimentally, using a confocal, a near-field optical microscope and a spectrometer, and theoretically, using FDTD methods. We show that triangular particles of noble metals are highly sensitive to the relative direction of incidence of light and its polarization. On the other hand, the light scattered in the direction perpendicular to the plane of the particles reveals strong spectral dependency. This dependency can be exploited to fabricate photonics devices sensitive to the direction of incidence of light.
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[46] Schmatulla, A., Maghelli, N. and Marti, O. (2007). "Micromechanical Properties of Tobacco Mosaic Viruses." Journal of Microscopy 225(3): 263-267.
marti_169.pdf  
A tobacco mosaic virus (TMV) subject to local forces can be viewed as an uniform beam with local loads. We used a custom built Atomic Force Microscope (AFM) to determine the curvature induced in the TMV by concentrated load or by distributed forces. Local forces were created by the AFM tip. Distributed forces were applied to the virus via the surface tension of receding droplets. The experimental results of both methods can be described when we attribute a Youngs modulus of 6 ± 3GPa to the virus. Our value is about 5 times larger than published data [1]. We compare our results to the literature and work out possible error sources in our experiment and in published one.
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[47] Boger, A., Heise, B., Troll, C., Marti, O. and Rieger, B. (2007). "Orientations of the alpha- and gamma- modification of Elastic Polypropylene at uniaxial stretching." European Polymer Journal 43(8): 3573-3586.
marti_168.pdf  
New metallocene catalysts applied to propene polymerization provide an expansion of the range of properties of polypropylene (PP), resulting in semi crystalline materials having crystallinity below 60% up to x-ray amorphous highly elastic ones. To date the origin of the unique elastic mechanical behavior of such low crystalline PP is sparsely known. Therefore, the microscopic orientation of those PPs due to uniaxial stretching was investigated using wide - (WAXS) and small angle x-ray scattering (SAXS) presented herein. The aim of this study was to correlate these orientations or changes in the developed fiber textures with the macroscopic stress strain behavior, for better understanding of the unique mechanical properties of those materials. This includes the efforts to come closer to the main question of the nature of the physical cross-links in these not chemical cross-linked homopolymers, which is the reason for the high elastic behavior. Therefore, high molecular weight metallocene PPs showing different crystallinity (0-36%) were stretched to several elongations and the structural changes during the deformation were recorded by x-ray scattering measurements. Stress strain measurements show the great potential of these novel PPs as a thermoplastic rubber material. For quantitative analysis and discussion of the polymer chain orientations, the orientation functions were calculated. Correlation between the orientation functions and the stress-strain curves allows the interpretation of the macroscopic behavior on the microscopic scale. Higher crosslink density due to higher chain orientations at elongation represent that the network, which is responsible for the elasticity, is mainly built up by strain-induced morphology changes and chain orientations. To our knowledge, this is the first study on elastic iPP that accounts chain orientations of stretched samples.
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[48] Gallyamov, M. O., Starodubtsev, S. G., Bragina, T. P., Dubrovina, L. V., Potemkin, I. I., Marti, O. and Khokhlov, A. R. (2007). "Conformational Behaviour of Comb-like Poly(4-vinylpyridinium) Salts and Their Complexes with Surfactants in Solution and on a Flat Surface." Macromol. Chem.Phys. 208: 164-174.
marti_165.pdf  
Poly(4-vinylpyridinium) bromides containing octyl and dodecyl pendant groups were synthesized. Bromide anions in these polymer salts were substituted with dodecylsulfate and bis(2-ethylhexylsuccinate) anions using ion-exchange reactions. Initial P4VP and its derivatives loaded with hydrophobic groups were deposited on a mica surface from dilute solutions in chloroform for visualization. Images of single adsorbed macromolecules were obtained using scanning force microscopy. Original P4VP chains form partially compacted self-intersecting coils. Attachment of large hydrophobic groups to the polymer chains and especially the increase of the number of alkyl tails (see Figure for Summary) per one monomer unit of the polymer chain leads to the stretching of the coils, and the resulted comb-like macromolecules adopt more and more extended self-avoiding 2D conformations when deposited on the substrate. Comparative statistical analysis was performed in order to determine the scaling exponents describing correlation between the contour length and the end-to-end distance of the adsorbed macromolecules. The viscosimetry data show that in contrast to the surface conformations, the comb-like polymers and their salts with dodecylsulfate in chloroform have even more compact conformations than the original P4VP.
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[49] Boger, A., Heise, B., Troll, C., Marti, O. and Rieger, B. (2007). "Mechanical and Temperature Dependant Properties, Structure and Phase Transitions of Elastic Polypropylenes." European Polymer Journal 43(2): 634-643.
marti_164.pdf  
A new metallocene catalyst applied to propene polymerization provides an expansion of the properties of polypropylene (PP) by generating semi-crystalline materials having 0-60% crystallinity. The purpose of the present study was to investigate such low crystalline elastomeric polypropylene (ePP) samples in order to compile further information on their crystal structure and the related phase transitions in the temperature range of 298 - 423 K. Calorimetric and stress strain measurements of mentioned ePP in comparison with high crystalline PP (Xc = 62%) confirms the new class of low crystalline PPs. These polymers combine the properties of a thermoplast, like excellent processability and ductility using heat, with those of elastomers. Temperature dependant WAXS investigations were carried out to determine crystallinity, crystalline structure, crystal modifications and crystal size in the temperature range from 298 to 423 K. As a function of temperature, apparent alpha - and gamma crystalline modifications were correlated and discussed concerning the phase transitions observed calorimetrically. The presented study includes calorimetric, tensile and x-ray scattering measurements of five metallocene PPs with crystallinities of 0, 5, 18, 36 and 62 %.
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[50] Gigler, A., Gnahm, C., Marti, O., Schimmel, T. and Walheim, S. (2007). "Towards quantitative materials characterization with Digital Pulsed Force Mode imaging." Journal of Physics: Conference Series 61: 346-351.
marti_163.pdf  
The determination of the mechanical properties of polymer-surfaces is a widespread task in the AFM community. The most important step in measuring is the thorough calibration of the measurement setup. Here, we address that problem for the case of Digital Pulsed Force Mode measurements. We show that following our suggestions, one can get reliable and consistent quantitative data on the mechanical properties of polymers such as PMMA or SBR rubber. The influence of the individual cantilevers and their properties, as well as the variations due to the settings of the AFM are widely eliminated.
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[51] Marti, O., Meinhard, D., Rieger, B. and Schmatulla, A. (2007). "Topology and Nanomechanics of Polyethylene Networks." Nanotechnology 18: 044013(7pp).
marti_162.pdf  
We show in this paper that three-dimensional networks in bulk polyethylene (mean molecular weight: 350000 g=mol, polydispersity of 2:62) with a defined grafting density of side-chains of 9.6% can be revealed by spin-coating the gel-like swollen polymer onto a flat surface. The polymer contained side chains with one (33%), two 20%), three (13%) and more (34%) carbon atoms. The polymer structure after spin-coating consists of bundles, droplets at interconnects and globules. The combined tapping mode and contact mode atomic force microscopy (AFM) is able to distinguish topological differences in interconnects, such as entangled junctions from simple crossings of polymer bundles. A solvent treatment of the polymer network on the sample surface reveals that some of the droplets are in fact superpositions of more than one droplet, indicating again that a tree-dimensional network is collapsed to two dimensions. We have observed, that polymer bundles do branch near such multiple droplets. Finally the recorded lateral forces while scanning across a polymer bundle in contact mode might be useful to model the mechanical behavior of polymer bundles. However, without a solid theoretical model it is difficult to translate the experimental data into meaningful materials properties.
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[52] Gigler, A., Holzwarth, M. and Marti, O. (2007). "Local nanomechanical properties of HeLa-cell surfaces." Journal of Physics: Conference Series 61: 780-784.
marti_161.pdf  
Using the Digital Pulsed Force Mode (DPFM) approach, the local mechanical properties of living HeLa cells have been examined. The cells were attached to a favorable glass-like substrate. The AFM used for the experiments was a commercial AFM setup by WITec. At every point of the image, approach and retract curves have been performed. The repeat rate of the cycle was 175 Hz. A total of about 500,000 curves has been recorded and completely evaluated for each experiment. The substrate served as an online reference material for calibration purposes. First, the force trajectories were corrected for the viscous drag force in the liquid environment. Second, the curves within the region of the substrate were phase corrected to compensate for the time lag of the signal in the setup assuming a purely elastic response of the reference material. Finally, all the force traces have been corrected by using this information and evaluated according to common continuum-elastic models. The resulting images allow the assignment of values of Young's modulus, local adhesion, hysteretic behavior, etc. at a high lateral resolution all over the cell body. In this paper, we describe the procedure of our measurement and the corresponding signal correction strategy of our automated data evaluation.
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[53] Asbach, G.-I. and Marti, O. (2006). Anleitung zum Grundpraktikum der Physik für Physiker. Ulm, Ulm University
marti_191.pdf
Original: http://vts.uni-ulm.de/docs/2000/441/vts_441.pdf
Die Anleitung zum Grundpraktikum Physik für Studierende in den Studiengängen Diplom Physik, Diplom Wirtschaftsphysik und Lehramt Physik wird im 3. und 4. Semester verwendet. Sie enthält Anleitungen zu folgenden Versuchen: Pendel und Rollschwingungen, Gekoppelte Pendel, Freie und Erzwungene Schwingungen mit dem Drehpendel, Drillachse, Viskosität von Flüssigkeiten, G-Modul von kristallinen Festkörpern (Metallen), Elastizitätskonstante von kristallinen Festkörpern, Oberflächenspannung, Kundtsches Staubrohr und Quinckesches Resonanzrohr, Bestimmung des Adiabatenexponenten von Gasen, Spezifische Wärme von Festkörpern und Flüssigkeiten, Latente Wärmen, Wärmeäquivalent, Schallmessung im akustischen Hohlraum mit der Rayleigh-Scheibe, Daten optischer Linsen und Spiegel, Geometrische Optik und optische Instrumente, Optische Instrumente, Polarisation und Doppelbrechung, Beugung, Michelson-Interferometer, Spektrometer, Temperaturstrahlung, Reflexion von Licht an Glas-Luft-Grenzflächen, Poggendorfsche Kompensationsmethode und Wheatstone-Brücke, Der Transformator, Kennlinien von Glühlampe, Z-Diode und Transistor, Zweipole, Elektromagnetische Schwingkreise, Elektrolytischer Trog
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[54] Holzwarth, M. J., Gigler, A. M. and Marti, O. (2006). "Digital Pulsed Force Mode - Determining Local Mechanical Properties of HeLa Cells." Imaging and Microscopy 8(4): 37-38.
marti_167.pdf  
Many AFM measuring modes have been developed recently. To test the capabilities of these techniques, experiments on the most suitable sample system have been conducted. For example, phase-imaging techniques have been mainly tested on phase-separating or dewetting polymer samples, while measurement modes based on the difference in electrical conductivity have been devised for semi-conducting surfaces or samples with changes in work function. Using the Digital Pulsed Force Mode (DPFM) approach, a nanoindentation technique, the typical scope of samples has also been on dewetting polymers, allowing the differentiation between the materials with respect to contact stiffness or adhesive properties. More interesting and also challenging, however, are the local mechanical properties of living matter. In the present work, living HeLa cells have been examined in a liquid environment.
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[55] Csete, M., Szekeres, G., Vass, C., Maghelli, N., Osvay, K., Bor, Z., Pietralla, M. and Marti, O. (2006). "Surface plasmon resonance spectroscopy on rotated sub-micrometer polymer gratings generated by UV-laser based two-beam interference." Applied Surface Science 252(13): 4773-4780.
marti_153.pdf  
Two-beam interference method was applied to generate gratings having periods of 416 and 833 nm by the forth harmonic of a Nd:Yag laser on thin poly-carbonate films spin-coated onto silver layer-covered substrates. The dependence of the modulation depth on the fluence and number of laser pulses was investigated by atomic force microscopy. A secondary pattern appeared on very thin polymer layers thanks to the ‘‘p’’ polarized laser beam induced self-organized processes. The conditions of the emergence of grating-coupling caused additional plasmon resonance peak were determined for the sub-micrometer periodic polymer gratings. Surface plasmon resonance measurements were performed in attenuated total reflection arrangement to determine the effect of the angle between the plasmon propagation direction and the polymer groves on the gratingcoupling. The effect of the modulation depth on the grating-coupling caused additional resonance minimum was also analyzed. We found coupling effects according to our calculations, the differences between the measured and theoretically predicted resonance curves were explained by the scattering effects on the complex surface structure.
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[56] Csete, M., Kurdi, G., Kokavecz, J., Megyesi, V., Osvay, K., Schay, Z., Bor, Z. and Marti, O. (2006). "Application possibilities and chemical origin of sub-micrometer adhesion modulation on polymer gratings produced by UV laser illumination." Mat. Sci. and Engin. C 26(5-7): 1056-1062.
marti_152.pdf  
Sub-micrometer periodic structures were prepared on the surface of poly-carbonate films by UV laser treatment methods: a) grating-like structures having a period of 156 nm were induced by ArF excimer laser, b) 416 and 833 nm periodic gratings were prepared by two-beam interference realized by the fourth harmonic of a Nd:Yag laser. The sub-micrometer adhesion pattern accompanying the topographical structure was determined by pulsed force mode atomic force microscopy. The difference between the measured adhesion modulation and the adhesion profile calculated based on the topography was explained by the UV laser illumination caused phase and chemical changes. XPS investigations proved that chemical modification of the polymer occurs and the degree of the photo-degradation depends on the treating laser wavelength as well as on the number and fluence of the laser pulses. It was demonstrated by tapping mode atomic force microscopy that bovine serum albumin attaches to surface parts having higher adhesion. The dependence of the protein adherence on the surface treatment conditions was demonstrated based on the C 1s and O 1s spectra and on the proteinaceous nitrogen level.
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[57] Kokavecz, J., Marti, O., Heszler, P. and Mechler, Á. (2006). "Imaging bandwidth of the tapping mode atomic force microscope probe." Physical Review B 73: 155403.
marti_141.pdf  
In this work we report a comprehensive experimental and computational study of the dynamical behavior of the tapping mode atomic force microscope (AFM) probe in interaction with the force field of a sample surface. To address the nonlinear nature of the probe dynamics, we apply describing function method. We established that the corner frequency of the low pass describing function of the probe is sensitive to the modulation amplitude and is generally higher than predicted by linear - force gradient - approximation. We show that large tip apex radii and high values of surface Young’s moduli can introduce a resonant amplitude transfer, which could lead to image distortion and system instabilities. We demonstrate that the oscillating amplitude of the probe far from the surface and during imaging, and the ratio of these two (setpoint) have an influence on the describing function of the probe similar to that of the quality factor. Accordingly, expert control of these parameters is as effective as active Q control in improving the imaging bandwidth of the tapping mode AFM.
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[58] Cobzaru, C., Hild, S., Boger, A., Troll, C. and Rieger, B. (2006). "Dual-side Catalysts for High and Ultrahigh Molecular Weight Homopolypropylene Elastomers and Plastomers." Coordinated Cemistry Review 250(1-2): 189-211.
hild-x10.pdf  
Classical Ziegler–Natta catalysts are capable of producing homopolypropylenes with high isotacticities. New trends are focussed on obtaining polypropylenes with different properties through control of the polymer microstructure. Metallocene catalysts with variable structures revealed a great potential toward this challenge. The flexibility of the indenyl ligand substitution proved to be the key in controlling the stereoerror formation. Error type and error distribution have major implications on the mean isotactic sequence length, and therefore also on the mechanical properties of the polymer products. Image This review focuses on the synthesis of asymmetric ansa-metallocene catalysts, their polymerization mechanism and chain transfer reactions. The impact of the presented asymmetric ansa-metallocene extends beyond simple propylene polymerization disclosing a way to materials that fill the gap between “soft” thermoplastic elastomers and stiff polypropylene materials.
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[59] Hild, S., Cobzaru, C., Troll, C. and Rieger, B. (2006). Elastomeric Homo-Polypropylene: Solid State Properties and Synthesis via Control of Reaction Parameters. Catalysis for Stereoregulating Polymerization. L. S. Baugh, J. M. Canich and E. B. Coughlin: submitted.
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[60] Hild, S., Cobzaru, C., Troll, C. and Rieger, B. (2006). "Elastomeric Poly(propylene) from ‘‘Dual-side’’ Metallocenes: Reversible Chain Transfer and its Influence on Polymer Microstructure." Macromolecular Chemistry and Physics 207(7): 665-683.
hild-x5.pdf  
The key to tailoring polymer properties such as stiffness, mechanical strength or transparency is to control the molecular architecture. For the polymerization of olefins, the development of metallocene catalysts gave access to ew polymer microstructures. One significant advantage in metallocene polymerization catalysis[1,2] is that the polymer microstructures and the corresponding material properties can be easily designed by variation of the catalyst structure.
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[61] Mainova, V., Hild, S., Reuter, P., Fuhrmann, R., Franke, R.-P. and Rieger, B. (2006). Synthesis of Functional Poly(1,4-ketone)s Bearing Bioactive Moieties by Pd-catalyzed Insertion Polymerization. MacromoleculesTo top

[62] Gotsmann, B., Hinz, M., Lantz, M. A., Duerig, U., Marti, O. and Windeln, J. (2005). Heat transfer experiments on micro- and nanoscale: Interface and size effects. American Physical Society, APS March Meeting, March 21-25, 2005.
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[63] Spizig, P., Sanchen, D., Förstner, J., Koenen, J. and Marti, O. (2005). Rastersonde in Pulsed Force Mode, Digital und in Echtzeit, Scanning probe with digitised pulsed-force mode operation and real-time evaluation, Sonde de balayage en mode digital de force pulsee et en temps reel. Europe, Witec GmbHmarti_155.pdf
Anmeldetag 12.12.2001 Veröffentlichung: 5. 1. 2005
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[64] Krotil, H.-U., Stifter, T. and Marti, O. (2005). Verfahren und Vorrichtung zur gleichzeitigen Bestimmung zumindest zweier Materialeigenschaften einer Probenoberfläche, umfassend die Adhäsion, die Reibung, die Oberflächentopographie sowie die Elastizität und Steifigkeit. Germany, Witec GmbHmarti_154.pdf
Anmeldetag: 5. 1. 1999 Offenlegungstag 3. 8. 2000 Patenterteilung 28. 7. 2005
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[65] Gigler, A. and Marti, O. (2005). Pulsed Force Mode SFM. SPMs beyond imaging. P. Samori.
marti_150.pdf
With the miniaturization of technological components, the ratio of surface area to the enclosed volume is increasing. Therefore, properties of surface features are becoming more and more interesting to scientists. Meanwhile lateral dimensions of several micrometers and surface roughnes of some tens of nanometers are common. Through the invention of Scanning Probe Microscopy (SPM) techniques, these dimensions became accessible. However, not only the topography of the samples can be investigated, but also its very local mechanical behavior. This possibility has driven scientists in every nanotech-lab to develop a broad range of operating modes for SPM systems. A variety of forces is involved in the interaction of the tip and the surface, such as elasto-mechanical forces, adhesion, electrochemical forces in the presence of electrolytes, and hydrodynamic forces such as the liquid neck between the tip-apex and the sample in ambient conditions. It is necessary to distinguish between these effects to understand the interaction and to separate artifacts from real data. This paper explores the capabilities of Pulsed Force Mode (PFM) data acquisition to get an almost complete characterization of tip-sample interactions, and thus, of sample materials.
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[66] Csete, M., Vass, C., Kokavecz, J., Goncalves, M., Megyesi, V., Bor, Z., Pietralla, M. and Marti, O. (2005). "Effect of sub-micrometer polymer gratings generated two-beam interference on surface plasmon resonance." Applied Surface Science 247(1-4): 477-485.
marti_148.pdf  
Sub-micrometer periodic gratings were generated on thin poly-carbonate films spin-coated onto thin flat silver layer covered BK7 substrates by two-beam interference realized with the fourth harmonic of the Nd:YAG laser. The 416nm period of the laser-induced grating was half of the applied master grating, the modulation depth was increased by the number of laser pulses at a given intensity. Attenuated total reflection measurements were performed in case of plasmon propagation directions parallel and perpendicular to the grooves, and on rotated gratings oriented at angles making the grating coupling effect detectable. Atomic force microscopy (AFM) was applied to determine the modulation depth of the gratings. It was shown that the periodically corrugated polymer surfaces resulted in the coupling of the surface plasmons already when the structure period was very close to the plasmon wavelength. The small shift of the resonance positions proved that the modulation depth cannot be explained by material removal, the material rearrangement plays an important role in the grating formation. These experimental results correlate with our temperature model calculations revealing that there is softening on the upper polymer surface and melting down to the silver layer at the lowest and highest applied laser fluences, respectively. [All rights reserved Elsevier]. (10 References).
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[67] Csete, M., Kresz, N., Vass, C., Kurdi, G., Heiner, Z., Deli, M., Bor, Z. and Marti, O. (2005). "Sub-micrometer adhesion modulation on polymer surfaces containing gratings produced by two-beam interference." Mat. Sci. and Engin. C 25(5-8): 813-819.
marti_147.pdf  
Grating-like structures having a period of 416 nm were produced on the surface of polycarbonate films by two-beam interference realized by the fourth harmonic of Nd:Yag laser. The period of the structures was half of the applied master grating, the ratio of the width of the valleys to the period was tuned by the intensity, the depth of the modulation was increased by the number of laser pulses. Pulsed force mode atomic force microscopy was applied to study the topography and the adhesion on structured surfaces with sub-micrometer resolution. The adhesion modulation caused by the topography was calculated along line cross-sections of the AFM pictures taking into account the tip and surface geometry. The separation of the effects of the topography and the laser induced material changes proved that the adhesion is increased at the areas illuminated by laser beam having a fluence above the melting threshold. The laser-induced material changes cause additional adhesion increase at the valleys of the structure. It was shown that the adherence of albumin results in dense packing on polycarbonate surface parts having sub-micrometer periodic adhesion modulation.
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[68] Cobzaru, C., Deisenhofer, S., Harley, A., Troll, C., Hild, S. and Rieger, B. (2005). "Novel High and Ultrahigh Molecular Weight Poly(propylene) Plastomers by Asymmetric Hafnocene Catalysts." Macromolecular Chemistry and Physics 206(12): 1231-1240.
hild-x6.pdf  
Asymmetric ansa-metallocene catalysts based on fluorenyl and specifically substituted indenyl ligands allow a continuous change in the properties of isotactic poly(propylene) and thus generate a new portfolio of poly(propylene) materials, ranging from excellent thermoplastic elastic to stiff plastomers. Controlling the length of crystallizable, isotactic segments by means of isolated stereoerrors introduced into the isotactic enchainment made this possible.
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[69] Heinemann, M., Voelkel, U., Barthel, H. and Hild, S. (2005). Silica Adhesion on Toner Surfaces Studied By Scanning Force Microscopy. Organosilicon chemistry. N. Auner and J. Weiss. VI: 910-919.
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[70] König, S. and Hild, S. (2005). Characterization of Silica-Polymer Interactions on the Microscopic Scale Using Scanning Force Microscopy. Organosilicon chemistry. N. Auner and J. Weiss. VI: 920-926.
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[71] Murphy, F., Kehoe, T., Pietralla, M., Winfield, R. and Floyd, L. (2005). "Development of an algorithm to extract thermal diffusivity for the radial converging wave technique." International Journal of Heat and Mass Transfer 48(7): 1395-402.
pi_2006.pdf  
The usual equation for the converging wave method [P. Cielo, L.A. Utracki, M. Lamontagne, Thermal diffusivity measurements by the converging thermal-wave technique, Canad. J. Phys. 64 (1986) 1172-1177] for thermal diffusivity measurements assumes idealised conditions that are difficult to achieve in a real experimental situation and this hinders the extraction of diffusivity values. A model for thermal transport is described here that takes into account errors due to heat losses and is relatively insensitive to detection position inaccuracy. A simple polynomial equation is derived from the model and it is used to generate initial guesses for the Levenberg-Marquardt algorithm, which uses these initial guesses to avoid a local minimum problem and ultimately produces a value for radial thermal diffusivity. [All rights reserved Elsevier] (18 References).
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[72] Schmidt, U., Hild, S., Ibach, W. and Hollricher, O. (2005). "Characterization of thin polymer films on the nanometer scale with confocal Raman AFM." Macromolecular Symposia 230(1): 133 - 143.
hild-x9.pdf  
The combination of an atomic force microscope (AFM) with a Confocal Raman Microscope (CRM) has been used to study the composition of various thin films of polymer blends. The high spatial resolution of the AFM enables the morphological characterization of the polymer blends on the nanometer scale. Furthermore, when operating the AFM in Digital Pulsed Force Mode (DPFM), topographic information and local stiffness can be simultaneously recorded. This allows the material-sensitive characterization of heterogeneous materials. Thin films where PMMA (at room temperature a glassy polymer) is blended with two different styrene-butadiene rubbers are investigated. The presence of PMMA in both phase-separated thin films allows the comparison of the mechanical properties of the two different rubber phases using DPFM-AFM. When PMMA is blended with PET due to their similar mechanical properties (both are in the glassy state at room temperature) the assignment of the two phases to the corresponding polymers by AFM is rather difficult. Here, Raman spectroscopy provides additional information on the chemical composition of materials. In combination with a confocal microscope, the spatial distribution of the various phases can be determined with a resolution down to 200 nm. Therefore, the topographically different structures observed in AFM images can be associated to the chemical composition by using the Confocal Raman Microscope (CRM).
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[73] Hopp, B., Smausz, T., Kokavecz, J., Kresz, N., Bor, Z., Hild, S. and Marti, O. (2004). "Investigation of incubation in ArF excimer laser irradiated poly(methyl-methacrylate) using pulsed force mode atomic force microscopy." Journal of Applied Physics 96(10): 5548-51.
marti_149.pdf  
An atomic force microscopic method to study the incubation states of UV laser irradiated polymer samples is presented. Targets were illuminated by different number of pulses at 5.8 and 8.9 mJ/cm/sup 2/ fluences. The induced adhesive and morphological changes were investigated simultaneously by an atomic force microscope equipped with a pulsed force mode extension. Importantly, below 100 pulses morphological changes were not observable while significant changes in the adhesion were found as a result of the incubation at 8.9 mJ/cm/sup 2/ fluence. This method allows the imaging and detection of the whole laser modified area with nanometer resolution. (26 References).
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[74] Kresz, N., Kokavecz, J., Smausz, T., Hopp, B., Csete, M., Hild, S. and Marti, O. (2004). "Investigation of pulsed laser deposited crystalline PTFE thin layer with pulsed force mode AFM." Thin Solid Films 453-454: 239-44.
marti_146.pdf  
Teflon thin films were prepared via pulsed laser deposition using an ArF excimer laser ( lambda =193 nm, FWHM=20 ns) from pressed powder pellets. The applied fluence was 6.25+or-0.23 J/cm/sup 2/, the number of pulses was 10000, the pressure in the vacuum chamber was 2*10/sup -5/ Torr and the substrate temperature was 250 degrees C. The layers were post-annealed at temperature within the range 320-500 degrees C. The atomic force microscopy and pulsed force mode atomic force microscopy (PFM) investigations demonstrated that the effective surface reaches its maximum at 320 degrees C. At higher temperatures (360-500 degrees C) it decreased significantly to an approximately constant value. Measuring the local adhesion the difference between the adhesion forces at 320 and 360 degrees C was kept within the error range. Increasing the annealing temperatures, the adhesion force decreased over the investigated range. Post-annealing of the samples at 360 degrees C resulted in highly crystalline spherulites with lateral dimensions of several hundred micrometers. By optimizing the heating and cooling rate during the annealing the average dimension of spherulites increased and ringed structures were obtained. The PFM measurements showed that the adhesion force increased significantly compared to the similar samples without ringed structures. (11 References).
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[75] Hild, S., Marti, O., Hollmann, F. and Rieger, B. (2004). "Effects of the chain microstructure on the properties of polyketones terpolymers characterized by Scanning Force Microscopy." European Polymer Journal 40(5): 905-916.
marti_145.pdf  
A new approach to tailor properties of polyketones is to modify their block structure by varying the polymerization process. ECO-PCO terblock copolymers with similar composition but different chain microstructure have been synthesized using either Pre Set Polymerization (PSP) or Pulsed Feed Polymerization (PFP). Whereas by PSP an ABC-triblock structure is obtained, the PFP results in [AB]n-multiblock structure. In this paper the influence of the chain microstructure in mechanical behavior and surface properties have be investigated. SFM phase images display a phase-separated bulk morphology where triblock polymers due to the larger blocks lenght form coarser structures than the multiblock samples. If the ECO content is above 50 % the sample partially crystalline lamellar structures can be found, which in case of the multiblock sample form a continuous network of lamellar-like ECO rich domains. All ECOPCO terpolymers reveal elastomeric behavior with an elastic recovery of at least 82 % but tensile strength and elongation vary with the block length of the chain microstructures. Differences in elasticity are explained by formation different amounts of cross-links consisting of blocks of parallel-aligned ECO chain segments or crystalline lamellae. It can be shown that the surface morphology differs from bulk morphology, mainly by the point that no distinc phase separtion appears but ECO rich domains can be detected. Surface tension measurements enable to correlate the surface energy with surface composition and surface morphology.
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[76] Hinz, M., Kleiner, A., Hild, S., Marti, O., Dürig, U., Gotsmann, B., Drechsler, U., Albrecht, T. R. and Vettiger, P. (2004). "Temperature dependent nano indentation of thin polymer films with the scanning force microscope." European Polymer Journal 40(5): 957-964.
marti_144.pdf  
The scanning force microscope (SFM) was used to investigate the temperature dependent micro mechanical properties of Polymethylmethacrylate (PMMA) films with a thickness of 35 nm in the range of the radius of gyration. Force distance curves were performed in the glass transition range to create permanent nanometric indentations with maximal forces up to 4µN. Quantitative measurements of the indentation depth during and after application of the force, hysteresis energy and slope of the loading part are carried out as function of sample temperature and applied force. The glass transition of the polymer film can be clearly identified by the change of the mechanical properties of the polymer. Surprisingly, only a small change of elasticity at the glass transition is observed.
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[77] Pai, R. K., Hild, S., Ziegler, A. and Marti, O. (2004). "Water-soluble terpolymer mediated calcium carbonate crystal modification." Langmuir 20: 3123-3128.
marti_139.pdf  
The structure of the polymeric substrate plays an important role in the nucleation of calcium carbonate crystals. In this study a synthetic water-soluble poly (acrylamide-co-2-acrylamido-2-methyl-1-propane sodium sufonate-co-n-vinyl pyrrolidone) was found to be a substrate favouring the nucleation of polymorphs of calcium carbonate crystals under specific experimental conditions. Morphological characterization of the polymorphs was done using Atomic Force Microscopy, Scanning Electron Microscopy, Energy Dispersive Spectroscopy, FTIR Analysis and X-ray Diffraction. If calcium carbonate is precipitated in the presence of terpolymer a remarkable increase in nucleation density (number of crystals per unit area) was observed. Stacked crystals of rhombohedral morphology were formed may be due to the presence of sodium sulfonate groups on the terpolymer. However, in the presence of poly-L-aspartic acid, almost all crystals are hollow and have needle like or plate like morphology was formed. This change in calcium carbonate morphology can be explained by the variation of the polymer conformation, if poly-L-aspartic acid is present.
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[78] Csete, M., Hild, S., Plettl, A., Ziemann, P., Bor, Z. and Marti, O. (2004). "The role of original surface roughness in laser-induced periodic surface structure formation process on poly-carbonate films." Thin Solid Films 453-454: 114-20.
marti_137.pdf  
Poly-carbonate films containing different types of original surface roughness were illuminated by a polarized ArF excimer laser beam having a fluence of 4 mJ/cm/sup 2/. Atomic force microscopy was applied to study the laser-induced periodic surface structure formation process at 0 degrees , 30 degrees and 45 degrees angles of incidence. The effect of initial surface structures on the intensity distribution was investigated in cases of: (a) grains on oriented and amorphous thick films; (b) holes on thin spin-coated films; and (c) nanoparticles arranged along micrometer long sides of hexagons below the spin-coated films. The presence of the scattering objects caused symmetry breaking, if the samples were illuminated by oblique incident 's' polarized beam. The Fourier analysis of the AFM pictures has shown the competition of structures having different periods. The characteristic of the permanent surface patterns proved that the interference of the incoming beam and the beams scattered on previously existing structures is the LIPSS generating feedback process. Ring-shaped structures having 228 nm diameter were produced. (8 References).
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[79] Hopp, B., Kresz, N., Kokavecz, J., Smausz, T., Schieferdecker, H., Doring, A., Marti, O. and Bor, Z. (2004). "Adhesive and morphological characteristics of surface chemically modified polytetrafluoroethylene films." Applied Surface Science 221(1-4): 437-43.
marti_135.pdf  
In the present paper, we report an experimental determination of adhesive and topographic characteristics of chemically modified surface of polytetrafluoroethylene (PTFE) films. The surface chemistry was modified by ArF excimer laser irradiation in presence of triethylene-tetramine photoreagent. The applied laser fluence was varied in the range of 0.4-9 mJ/cm/sup 2/, and the number of laser pulses incident on the same area was 1500. To detect the changes in the adhesive features of the treated Teflon samples, we measured receding contact angle for distilled water and adhesion strength, respectively. It was found that the receding contact angle decreased from 96 degrees to 30-37 degrees and the adhesion strength of two-component epoxy glue to the treated sample surface increased from 0.03 to 9 MPa in the applied laser fluence range. Additionally, it was demonstrated that the adhesion of human cells to the modified Teflon samples is far better than to the untreated ones. The contact mode and pulsed force mode atomic force microscopic investigations of the treated samples demonstrated that the measured effective contact area of the irradiated films does not differ significantly from that of the original films, but the derived adhesion force is stronger on the modified samples than on the untreated ones. Hence, the increased adhesion of the treated Teflon films is caused by the higher surface energy. (17 References).
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[80] Bhushan, B. and Marti, O. (2004). Scanning Probe Microscopy - Principle of Operation, Instrumentation, and Probes. Springer Handbook of Nanotechnology. B. Bhushan. Heidelberg, Springer-Verlag: 325-369.
marti_134.pdf
Since the introduction of the STM in 1981 and AFM in 1985, many variations of probe based microscopies, referred to as SPMs, have been developed. While the pure imaging capabilities of SPM techniques is dominated by the application of these methods at their early development stages, the physics of probe–sample interactions and the quantitative analyses of tribological, electronic, magnetic, biological, and chemical surfaces have now become of increasing interest. Nanoscale science and technology are strongly driven by SPMs which allow investigation and manipulation of surfaces down to the atomic scale. With growing understanding of the underlying interaction mechanisms, SPMs have found applications in many fields outside basic research fields. In addition, various derivatives of all these methods have been developed for special applications, some of them targeted far beyond microscopy. This chapter presents an overview of STM and AFM and various probes (tips) used in these instruments, followed by details on AFM instrumentation and analyses.
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[81] Krotil, H. U., Stifter, T. and Marti, O. (2004). Verfahren und Vorrichtung zur gleichzeitigen Bestimmung der Adhäsion, der Reibung und weiterer Materialeigenschaften einer Probenoberfläche. Germany, WITec GmbHmarti_119.pdf
Anmeldetag: 4. 1. 2000 Offenlegungstag 10. 10. 2001 Patenterteilung 27. 10. 2004
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[82] Perez-Foullerat, D., Hild, S., Mücke, A. and Rieger, B. (2004). "Synthesis and Properties of Poly(ketone-co-alcohol) Materials: Shape Memory Thermoplastic Elastomers by Control of the Glass Transition Process." Macromol. Chem. Phys. 205: 374-382.
hild_2004.pdf  
Summary: The well-controlled reduction of polyketone carbonyl functional group was performed without chain degradation by using NaBH4 in tetrahydrofuran (THF)/MeOH solvent mixtures. Three different families of flexible polyketones (alternating propene/CO PCO, hex-1-ene/CO HxCO copolymers, and pulse feed alternating olefin/CO terpolymers from ethene and propene EPCO) were investigated to achieve either a partial reduction, leading to poly(ketone-co-alcohol)s of corresponding composition, or a complete conversion into polyalcohols. Increasing the ratio of [OH]/[CO] functions allows continuous change of the Tg of the resulting polymers from below room temperature to about 75 °C. Properties of the synthesized materials, like thermal decomposition, glass transition temperature, surface tension, and mechanical performance, are described depending on the degree of reduction. Thermoplastic elastomers with an interesting shape memory effect result from the partially reduced, elastic EPCO terpolymers.
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[83] Pérez-Foullerat, D., Meier, U. W., Hild, S. and Rieger, B. (2004). "High-Molecular-Weight Polyketones from Higher alpha-Olefins: A General Method." Macromolecular Chemistry and Physics 205(17): 2292-2302.
hild-x7.pdf  
Studies of 1,4-polyketone materials have so far been focused on ethene/carbon monoxide systems (ECO). Nowadays, the well-known, commercial, aliphatic, polyketone materials are semicrystalline thermoplastics with unique properties, like excellent mechanical and chemical resistance. In spite of that, materials arising from the copolymerization ofCO with olefins other than ethene have been only sporadically a matter of scientific reports (with the exception of styrene).
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[84] Stenert, M., Döring, A. and Bandermann, F. (2004). "Poly(methyl methacrylate)-block-polystyrene and polystyrene-block-poly(n-butyl acrylate) as compatibilizers in PMMA/PnBA blends." e-Polymers 15: 1-16.
doering_2004.pdf  
The influence of the addition of poly(methyl methacrylate)-block-polystyrene (PMMA-b-PS) and PS-b-poly(n-butyl acrylate) (PS-b-PnBA) diblock copolymers on the structure and the mechanical properties of PMMA/PnBA polymer blends was investigated. In binary polymer blends of PMMA and PS, and PS and PnBA, and in the ternary system the corresponding diblock copolymers caused a significantly higher distribution of the dispersed phase and an appreciable narrowing of the particle size distribution as shown by scanning force microscopy using the pulsed force mode technique. Transmission electron microscopy images proved that in the ternary system the two diblock copolymers formed no own separate phase but are arranged as a ring layer at the interface between the two homopolymers PMMA and PnBA. Charpy tests demonstrated that the impact strength of the ternary blends is increased by the two diblock copolymers even at low amounts of the latter. The influence on mechanical properties like Young's modulus, yield stress, and tensile strength at break was less marked as strain-stress measurements showed. The major effect seems to be exerted on the elongation at break.
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[85] Csete, M., Kokavecz, J., Bor, Z. and Marti, O. (2003). "The existence of sub-micrometer micromechanical modulation generated by polarized UV laser illumination on polymer surfaces." Materials Science & Engineering C 23: 939-944.
marti_143.pdf  
Sub-micrometer grating-like structures were generated on the surface of poly-carbonate (PC) films by polarized ArF excimer laser illumination well below the material ablation threshold. The period of the laser-induced surface structures was tuned by modifying the angle of incidence of the laser beam. The depth of the modulation was enlarged increasing the number of the laser pulses. The surface changes caused by the laser illumination were investigated by atomic force microscope operating in pulsed force mode. It was proven that not only the topography, but also the micromechanical properties are modulated with sub-micrometer period. Interestingly, the measured adhesion modulation is different from the adhesion modulation calculated by taking into account the tip and sample geometry. The co-existence of a reversed adhesion modulation was proven: the adhesion is increased at the hills caused by material changes, which may over-compensate the topographical effects. FTIR investigations have shown that chemical changes accompany the phase transitions leading to the structure formation.
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[86] Csete, M., Eberle, R., Pietralla, M., Marti, O. and Bor, Z. (2003). "Attenuated total reflection measurements on poly-carbonate surfaces structured by laser illumination." Applied Surface Science 208-209: 474-480.
marti_140.pdf  
Periodic structures were studied on spin-coated poly-carbonate (PC) films: (a) sub-micrometer laser induced periodic surface structures (LIPSS) were generated by polarized ArF excimer laser beam; (b) micrometer periodic lines were ablated by imaging a mask onto the samples. The change in the thickness and the surface roughness was determined by an attenuated total reflection setup. The difference between the resonance places measured on the structured and untreated surfaces was very small in the case (a), proving that there is no significant material removal during LIPSS formation. The plasmon scattering caused by the sub-micrometer roughness weakly depends on the direction of the plasmon propagation. The broadening of the resonance curve started after 400 laser pulses, the roughness increased up to 800 laser pulses and after 1000 pulses the curve became more narrow corresponding to the changes in the topography detected by atomic force microscopy. The shift of the resonance peak measured on the ablated samples (b) indicated a change in thickness corresponding to the rate of ablation. The effect of the micrometer structures on the broadening of resonance curves depends on the direction of plasmon propagation
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[87] Hild, S., Heinemann, M., Voelkel, U. and Barthel, H. (2003). Adhesion of silica particles and silylated silicon tips on model toner surfaces - a SFM study. IS&T's NIP19: International Conference on Digital Printing Technologies, Springfield, VA, USA., IS&T: Soc. for Imaging Sci. and Technol.
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[88] Gonçalves, M. R. and Marti, O. (2003). "Scattering of Light by planar metallic nanoparticles." New Journal of Physics 5: 160.1-160.14.
marti_136.pdf  
It is known that the efficiency of scattering of light by a particle is related to its size, geometry and optical constants of the material, since the theory of scattering by small particles developed by Mie in the beginning of the 20th century. However, the Mie scattering theory is valid just for a few special cases like a homogeneous sphere embedded on a medium of homogenous refraction index. More recently, some theoretical simulations on planar nano- particles have shown that the optical resonances are dependent on the shape of the particle. Simultaneously, local field enhancements take place on the particles when excited by an incident wave. A comprehensive knowledge of the optical behaviour of planar particles is of great importance for the development of optical devices at the nanoscale, as well as for the fast developing field of photonic crystals and the emerging field of diffractive optics. In this paper, we present optical investigations on arrays of triangular nanoparticles with sizes comparable with the wavelength. Particles were produced using the method developed by Fischer and the optical measurements have been made using a scanning confocal microscope and a total-internal-reflection system. The scattering of light by particles of some materials when excited by an evanescent field show a strong dependence on their relative orientation in the direction of incidence. The measured scattering patterns change with the polarization of light.
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[89] Hild, S., Voelkel, U., Heinemann, M. and Barthel, H. (2003). Adhesion of Silica Particles and Silylated Silicon Tips on Model Toner Surfaces - a SFM Study. IS&T's NIP19 International Conference on Digital Printing Technologies.
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[90] Spizig, P., Sanchen, D., Foerstner, J., Koenen, J. and Marti, O. (2002). Procedure for the illustration of a sample/test surface with the help of a raster probe as well as raster probe microscope. DE 10062049, Witec Wissenschaftliche Instrumente Und Technologie Gmbh, Germanymarti_151.pdf
The invention concerns a procedure for the production of the illustration of one sample/test surface with a dissolution, which can be examined, which is laterally to the sample/test surface better as 1 mm and vertically to the surface better than 100 Nm. The surface is point-like scanned by a raster probe, whereby at each raster point of the sample/test surface the distance/spacer between raster probe and sample/test surface is periodically modulated, so that for this point a force time curve of the probe results. The force time curve is taken up at each raster point and digitized by means of a A/D transducer and put down in a first range of a storage facility. From the put down, digitized force time curve one or more characteristic sizes of the force time curve for each raster point are determined and received from these characteristic sizes of the raster points an illustration of the sample/test surface.
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[91] Marti, O. (2002). Buchbesprechung: Big Business und Big Bang by M.Rauner, S.Jorda. Physik in unserer Zeit. 33: 195
marti_174.pdf
Das heutige Berufsbild des Physikers ist außerordentlich vielfältig. Das belegen Reportagen von Physikern und Personalverantwortlichen, die einen Teil dieses Buches ausmachen. In zahlreichen Fallstudien aus unterschiedlichen Bereichen, wie der Unternehmensberatung, der Halbleiterindustrie, dem Patentwesen, dem Finanzwesen oder der Softwarebranche, aber auch aus der Kunst,werden Arbeitsalltag und Karrierechancen sowie das Umfeld und die Verdienstmöglichkeiten von Physikern vorgestellt.
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[92] Riethmuller, S., Mourran, A., Moller, M., Levi, S. A., Reinhoudt, D. N., Gonçalves, M. and Marti, O. (2002). Selective bonding of fluorescent molecules on gold surfaces. 224th ACS National Meeting, Boston, MA, United States, American Chemical Society.
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[93] Vargas, F., Hollricher, O., Marti, O., de Schaetzen, G. and Tarrach, G. (2002). "Influence of protective layers on the blinking of fluorescent single molecules observed by confocal microscopy and scanning near field optical microscopy." Journal of Chemical Physics 117(2): 866-871.
marti_133.pdf  
Transitions of fluorescent Rhodamine 6G dye molecules into metastable dark states with lifetimes of several seconds were observed by single-molecule detection (SMD) using far-field confocal microscopy. The samples were protected with different organic thin films and were characterized using atomic force microscopy. The data are compared to published models: The best fit is found with a model suggesting that oxygen migration or polarity changes are responsible for the transitions. For further studies with molecules close to each other, we studied the capability of cantilever-SNOM sensors for SMD. Using an a-SNOM we were able to demonstrate 40 nm optical resolution of these new near-field tips for single-molecule fluorescence imaging in direct comparison with confocal microscopy on samples of Rhodamine 6G molecules protected by PMMA.
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[94] Anders, S. H., Eberle, R., Peetz, L., Krüger, J.-K., Göschel, U. and M., P. (2002). "Anisotropic properties of poly(ethylene terephthalate) by Brillouin spectroscopy: anisotropic properties of oriented bulk and nanostructured poly(ethylene terephthalate) determined by Brillouin spectroscopy and birefringence experiments." Journal of Polymer Science, Part B (Polymer Physics) 40(12): 1201-1213.

Using Brillouin spectroscopy (BS), the tensor of the elastic constants of oriented poly(ethylene terephthalate) was determined for a variety of morphologies obtained by different uniaxial drawing procedures. The extreme values of the moduli along the drawing direction at frequencies of a few gigahertz were C/sub 33/ = 40 GPa and C/sub 44/ = 1.8 GPa. As a result of the invariants of the single-phase aggregate model, the oriented state is dominated by the Reuss average even at extreme draw ratios and subsequent to a deformation-induced crystallization. This is documented in both the BS orientation parameter and the BS mode numbers in comparison with birefringence. Additional spectral lines observed at draw ratios larger than 6 are discussed in relation to the formation of nanostructured phases
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[95] Eberle, R., Kresser, T. and Pietralla, M. (2002). "Elastic properties of thin silver films: hexagonal model and influence of corrugation effects." Thin Solid Films 408(1-2): 169-175.

Silver films on a glass substrate with a thickness range of 34-900 nm were examined using Brillouin spectroscopy. The surface plasmon resonance was used to determine the thickness of the thinner films very accurately and to enhance the Brillouin signal. With a special scattering setup, the Rayleigh and first Sezawa mode could be observed over a wide wavevector range. From the two dispersion branches, the elastic constants c/sub ij/ were determined, assuming a hexagonal symmetry. It transpired that the mechanical properties of the films were dependent on film thickness. The elastic constant c/sub 44/ shows a systematic behavior-starting nearly from the isotropic value, it decreases with decreasing film thickness. The hexagonal model works well for films thicker than 60 nm and the lowered value for c/sub 44/ can be satisfactorily explained by a preferred <111> orientation of the silver crystallites. However, for the thinnest films, the crystallite orientation cannot explain the strong decrease solely in C/sub 44/. Other effects, like surface roughness, become important
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[96] Hild, S., König, S., Imhof, C. S., Heinemann, M., Voelkel, U. and Barthel, H. (2002). Silica Adhesion on Toner Surfaces studied by Scanning Force Microscopy. IS&T's NIP18 International Conference on Digital Printing Technologies.
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[97] Hild, S., Schroth, K. and Döring, A. (2002). Investigating the microscopic properties of thermoplastic elastic polymers using Pulsed Force Mode SFM. Proc. of ACS, Rubber Division161st Spring Technical Meeting, ACS.
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[98] Allegrini, M., Garcia, N. and Marti, O., Eds. (2001). Proceedings of the International School of Physics "Enrico Fermi" Course, Nanometer Scale Science and Technology, held 27 June-7 July 2000 at Varenna on Lake Como, Italy.

[99] Kröner, P., Baumeister, H., Rieger, J., Veuhoff, E., Marti, O. and Heinecke, H. (2001). "Heterointerface optimization in InP based strained MQW laser structures using metalorganic growth technologies." Conference Proceedings(01CH37198): 296-8.

Epitaxial growth of InP based strained MQW laser structures is studied for metalorganic vapor phase epitaxy (MOVPE) and metalorganic molecular beam epitaxy (MOMBE or CBE-chemical beam epitaxy). For a tensile barrier layer strain of | epsilon /sub B/|>or=0.4% both in MOVPE and MOMBE, wavy MQW interfaces are observed in TEM along with a severe drop in photoluminescence (PL) intensity and an increase in PL FWHM (full width at half maximum) yielding a significant increase in threshold current density of broad area test lasers. Lateral thickness modulations appear to be much larger in MOVPE than in MOMBE. The V/III ratio appears to be a key parameter for the rate of wavy interface development, which is probably a consequence of surface selective growth. Flat interfaces require low V/III ratios, especially at high strain in the barrier layers resulting in a significant improvement in threshold current density
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[100] Simon, A., Brunner, R., White, J. O., Hollricher, O. and Marti, O. (2001). "Shear-force distance control at megahertz frequencies for near-field scanning optical microscopy." Review of Scientific Instruments 72(11): 4178-82.
marti_131.pdf  
We show that the use of fiber overtone resonance modes up to 3 MHz for shear-force distance control has two advantages for near-field microscopy. The higher dither frequency allows a shorter feedback loop time delay, which in turn allows scanning speeds of 100 mu m/s on a sample with, for example, a 150 nm height variation over a 1 mu m distance. Experiments on a hard semiconductor device and on a soft polymer sample demonstrate a factor of 5 improvement in scanning speed when the dither frequency is increased by a factor of 20. The second advantage is a reduction of the minimum lateral force required for height regulation, which is important for soft samples. Modeling the piezoelectric detection system as a harmonic oscillator indicates a factor of 33 increase in lateral force sensitivity when using the third overtone resonance of a typical fiber tip. This result is confirmed experimentally by immersing the tip into water
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[101] Marti, O. and Krotil, H.-U. (2001). Dynamic friction measurement with the scanning force microscope. Fundamentals of Tribology and Bridging the Gap between the Macro- and Micro/Nanoscales. B. Bhushan. Dordrecht, Kluwer Academic Publisher: 121-135.
marti_130.pdf
Scanning Force Microscopes excert lateral forces on the sample during measurement. The recording of the magnitude of these forces as a function of position gives friction maps. The possible scanning speeds of SFM, how-ever, are far below the velocities of practical devices. The dynamic friction force measurement provides a solution to this problem. The sample is mod-ulated laterally at frequencies up to several kilohertz and with amplitudes in the nanometer range. It is shown that the interaction with the sample is not only determined by friction, but also by the viscoelastic response of the sample. The combination of dynamic friction measurement with the inter-mittent contact measurement mode, the PulsedForceMode, gives full access to the relevant sample parameters: topography, lateral ‘friction’ forces, ad-hesion, sample stiffness and relaxations times.
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[102] Krotil, H.-U. and Marti, O. (2001). "Dynamic Friction measurements with the AFM on polymer surfaces." J. Synthetic Lubrication 18(1): 1-15.
marti_109.pdf  
The combination of scanning friction force microscopy (SFFM) with lock-in techniques leads to dynamic SFFM (DSFFM) and provides great advantages in friction force studies with sub-pm resolution. We present measurements on thin adsorbed organic films, on polymers (polymer blend of 75% poly(allylaminehydrochloride), PAA and 25% Poly(diallyl-dimethylammoniumchloride), PDDAC) and on mica (as a reference) The amplitude and phase response as a function of the excitation amplitude can be explained on hard surfaces by a simple static and dynamic friction model. This model aliows us to further distinguish static friction forces and kinetic friction forces in a quantitative way. Further more we demonstrate the use of these spectra to determinate the correct modulation amplitude of the excitation to achieve the optimal frictional contrasts directly. Polymer data suggest that the viscoelastic shear flow under the AFM tip is responsible for the shape of the phase and amplitude spectrum. Lastly we demonstrate that DSFFM is a useful technique for surface characterization in situations where SFFM may not be adequate.
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[103] Csete, M., Marti, O. and Bor, Z. (2001). "Laser-induced periodic surface structures on different poly-carbonate films." Applied Physics A (Materials Science Processing) A73(4): 521-6.
marti_128.pdf  
Laser-induced periodic surface structures (LIPSS) were generated on oriented and amorphous thick, as well as on spin-coated thin, poly- carbonate films by polarized ArF excimer laser light. The influence of the film structure and thickness on the LIPSS formation was demonstrated. Below a critical thickness of the spin-coated films the line-shaped structures transformed into droplets. This droplet formation was explained by the laser-induced melting across the whole film thickness and subsequent de-wetting on the substrate. The thickness of the layer melted by laser illumination was computed by a heat-conduction model. Very good agreement with the critical thickness for spin-coated films was found. The original polymer film structure influences the index of refraction of the thin upper layer modified by the laser treatment, as was proven by the dependence of the structure's period on the angle of incidence both for `s'- and `p'-polarized beams. The effect of the original surface roughness-grains in thick films or holes in thin films-was studied using atomic force microscopy. It was shown that the oblique incidence of `s'-polarized beams results in an intensity confinement in the direction of the forward scattering and in asymmetrical interference pattern formation around these irregularities. A new, two-dimensional grating-like structure was generated on spin- coated films. These gratings might be used as a special kind of mask
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[104] Likodimos, V., Labardi, M., Orlik, X. K., Pardi, L., Allegrini, M., Emonin, S. and Marti, O. (2001). "Thermally activated ferroelectric domain growth due to random defects." Physical Review B 63(6): 064104.
marti_125.pdf  
Ferroelectric domain kinetics on cleaved triglycine sulfate, quenched at different temperatures in the ferroelectric phase, is investigated {\it in situ} by scanning force microscopy in the dynamic contact mode. Thermally activated domain growth and dynamic scaling, in accordance with theoretical predictions for quenched disorder due to random-bond defects, is inferred from the temporal evolution of the spatial correlation functions and the related characteristic length scale.
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[105] Krotil, H.-U., Stifter, T. and Marti, O. (2001). "Lock-in technique for concurrent measurement of adhesion and friction with the scanning force microscope." Review of Scientific Instruments 72(1): 150-156.
marti_124.pdf  
Regardless of all the great progress in new scanning probe microscopy techniques, the concurrent measurement of adhesive and frictional forces with local resolution using scanning force microscopy (SFM) has not been possible until now. In this paper, we present a novel scanning probe microscopy mode, called combined dynamic x mode or CODYMode®. In CODYMode® SFM at least two oscillations with sufficiently different frequencies and amplitudes are superimposed and interact with the sample surface. This enables the concurrent measurement of the topography, adhesive and frictional forces beside further mechanical surface properties of the sample. By means of the characterization of plasma treated biaxially oriented polypropylene foils the benefits of the new modulation technique are pointed out where common SFM techniques are not adequate. As second application high-velocity friction experiments (in the range of several centimeters per second) on silicon under controlled environmental conditions are introduced and the role of the native water film on it is discussed under friction and viscoelastic aspects. ©2001 American Institute of Physics. 10.1063/1.1329898]
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[106] Emonin, S., Held, T., Richard, N., Hollricher, O. and Marti, O. (2001). "Multicolor images acquisition by scanning near-field optical microscopy." Journal of Applied Physics 90(9): 4820- 4.
marti_121.pdf  
A multicolor scanning near-field optical microscope (color-SNOM) has been developed to provide real color images of nanoscopic samples for biological and spectroscopical purposes. The sample illumination consists either of a single or a combined beam of different laser wavelengths. A common SNOM setup has been modified in a way that three photomultipliers for blue, green, and red light detection and color separating dichroic filters have been implemented. With this beam splitter device, it is possible to acquire simultaneously with the topography three color optical images on three different channels. In order to improve the signal-to-noise ratio, etched fiber tips with a high transmission intensity were used. Fluorescence experiments on latex beads labeled with two different dyes and transmission measurements on gold nanoparticles show a wavelength dependent optical contrast. The color-SNOM appears as a powerful tool for high resolution color spectroscopy
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[107] Barth, P. (2001). Verfahren zur Oberflächenstrukturierung. Deutschlandbarth_2001.pdf
Es wird ein Mikrodruckverfahren zur Strukturierung oxidierter Oberflächen (18) mittels eines Stempels (14) beschrieben, dessen Oberfläche (16) die zur Strukturierung erforderlichen Strukturinformationen umfaßt und mit Silan- oder Thiolmolekülen benetzt wird, die durch In-kontaktbringen der Stempeloberfläche (16) mit einer zu strukturierenden Oberfläche (18) ("Stempeln") auf diese übertragen werden. Erfindungsgemäß werden hierbei zumindest zwei über schwache Wechselwirkungen miteinander verbundene Monolagen Silan- bzw. Thiolmoleküle (10a, 10b) orientiert auf die Stempeloberfläche (16) aufgebracht, die vorher vorzugsweise einer Plasmaoxidation unterworfen wird. Beim Stempeln wird vorzugsweise lediglich eine einzige Monolage (10b) übertragen, wobei homogene, planare Molekülstrukturen im Nanometerbe-reich mit einer definierten lateralen Strukturabgrenzung entstehen. Zudem wird ein insbesondere zur Strukturierung einer Stempeloberfläche (16) geeignetes Oberflä-chenstrukturierungsverfahren beschrieben, bei dem Strukturinformationen im Nanometerbereich durch ein Plasmaoxidationsverfahren übertragen werden. Die zu übertragenden Strukturinformationen sind hierbei vorzugsweise in einer geeignet strukturierten Goldfolie oder einer sonstigen Metallfolie gespeichert.
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[108] Heinemann, M., Barthel, H., Voelkel, U. and Hild, S. (2001). Morphology of Toner-Silica Interfaces. IS&T's NIP17 International Conference on Digital Printing Technologies.
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[109] Luginbühl, R., Garrison, M. D., Overney, R. M., Weiss, L., Schieferdecker, H., Hild, S. and Ratner, B. D. (2001). Chemical and Contact Mechanical Characterization of Thin Plasma-Deposited Hexafluoropropylene Films. Fluorinated Surfaces, Coatings and Films. D. G. Castner and D. W. Grainger, American Chemical Society. 787: 187-202.
hild_2001.pdf
Hexafluoropropylene (HFP) was deposited in a radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) process as a function of applied reactor energy. The resulting polymer films were investigated regarding chemical composition with the electron spectroscopy for chemical analysis (ESCA). Photolithographic masking of silicon with subsequent deposition of HFP plasma polymer allowed for creating of micropatterned plasma films. The films were inspected with the scanning force microscope (SFM) regarding film thickness and surface roughness. In addition, the adhesion forces between SFM tip and the patterned substrates were probed via Pulsed Force Microscopy (PFM). The chemical composition and mechanical properties were found to be dependent on the plasma polymerization conditions. These properties were compared and related to the measured adhesion forces.
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[110] Spizig, P., Sanchen, D., Förstner, J., Koenen, J. and Marti, O. (2001). Rastersonde in Pulsed Force Mode, Digital und in Echtzeit. Europa, Witec GmbHTo top

[111] Krotil, H.-U., Stifter, T. and Marti, O. (2000). Method and device for simultaneously determining the adhesion, friction, and other material properties of a sample surface. PCTTo top

[112] Kröner, P., Baumeister, H., Gessner, R., Rieger, J., Schier, M., Veuhoff, E., Marti, O. and Heinecke, H. (2000). Mechanisms in embedded selective epitaxy and overgrowth of an integrated laser/modulator quantum well structure using MOMBE and MOVPE. MRS Fall Meeting, Boston, Massachusetts, MRS.
marti_127.pdf
Lateral integration of optoelectronic devices comprising strained multiple quantum well (MQW) structures can most successfully be accomplished by selective area epitaxy using metal organic molecular beam epitaxy (MOMBE). We optimized the growth parameters with respect to a planar butt coupling and sharp, flat MQW interfaces in an integrated MQW laser / MQW modulator structure. Defect generation in metal organic vapor phase epitaxy (MOVPE) overgrown cladding layers is analyzed and shown to contain information about the quality of the buried butt coupling. A ridge waveguide structure has successfully been fabricated from an optimized integrated laser / modulator structure.
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[113] Krotil, H.-U., Stifter, T. and Marti, O. (2000). "Combined dynamic adhesion and friction measurement with the scanning force microscope." Applied Physics Letters 77(23): 3857-3859.
marti_126.pdf  
In this letter, we present a promising scanning probe microscopy mode, called combined dynamic X mode or short CODYMode®. In CODYMode® scanning force microscopy, at least two modulations with sufficiently different frequencies and amplitudes are superpositioned and interact with the sample surface. This enables the concurrent measurement of the topography, adhesive and frictional forces, and further mechanical surface properties of the sample. The general advantages of CODYMode® are discussed. This technique is predestined for investigation of delicate samples (polymers, biological samples, etc.) in which common scanning force microscope techniques are not adequate. An ABC-triblock copolymer system served as sample system. ©2000 American Institute of Physics.
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[114] Marti, O. (2000). Experimental techniques in Near Field Optics. "Nanometer scale science and technology. M. Allegrini, N. García and O. Marti. Varenna, SOCIETÀ ITALIANA DI FISICA. CXLIV.
marti_123.pdf
Experiments using light to probe atoms, molecules or extended samples provide an excellent energy resolution. The wavelength of the light, however, sets a lower limit to the area probed perpendicular to the direction of propagation. This limit is of the order of the wavelength of the light. When experimenting with single molecules, one has to lower their concentration to the point where it is possible to probe one specimen alone. Scanning probe microscopes, on the other hand, have a superb spatial resolution. Near field optical microscopy, around for 15 years now, combines the energy resolution of optics with, to certain extent, the spatial resolution of scanning probe microscopy. Recent developments on the instrumental side promise reliable instruments based on reproducible batch fabricated sensors. This paper will outline the instrumental aspects, discuss some concepts of the instrumental setup, the probe fabrication and some selected applications in the fields of polymer and semiconductor physics.
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[115] Stifter, T., Marti, O. and Bhushan, B. (2000). "Theoretical investigation of the distance dependence of capilary and van der Waals forces in SFM." Physical Review B 62(20): 13667-13673.
marti_122.pdf  
The capillary and van der Waals forces between a tip and a plane in a scanning force microscope (SFM) are calculated. The forces are calculated for a fixed distance of tip and sample, as well as during retracting of the tip from the sample surface. The exact geometric shape of the meniscus is considered, with the boundary condition of fixed liquid volume during retraction. The starting volume is given by the operating and environmental conditions (surface tension, humidity, and tip geometry) at the point of lowest distance between tip and surface. The influence of the different parameters, namely, humidity, tip geometry, tip-sample starting distance, surface tension, and contact angles are studied. For each force curve also the geometric shape of the meniscus is calculated. The capillary forces are compared with van der Waals forces to understand their relative importance in various operating conditions. In addition to application in SFM, this analysis is useful in the design of surface roughness in microdevices for low adhesion in operating environments. ©2000
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[116] Krotil, H.-U., Stifter, T. and Marti, O. (2000). "Concurrent measurement of adhesive and elastic surface properties with a new modulation technique for scanning force microscope." Review of Scientific Instruments 71(7): 2765-2771.
marti_120.pdf  
The combination of two well-established dynamic scanning force microscopy (SFM) modes is incorporated for SFM in combined dynamic X mode or CODY Mode® SFM. A vertical modulation of low frequency and large amplitude is superimposed with a second vertical modulation of high frequency and low amplitude leading to a combination of pulsed force mode SFM, force modulation, and phase sensitive SFM. SFM in the new mode allows the simultaneous mapping of a number of physical surface properties including adhesive force and elasticity over one scan. The new SFM technique is nondestructive and alteration or even destruction of the sample surface is reduced to a minimum. A polymer blend (two homopolymers spin coated on silicon from a tetrahydrofuorane solution of a mixture of poly-2-vinylpyridin and polytertbutylmethacrylate) was used as a sample for comparative measurements between pulsed force mode, force modulation mode and the new SFM mode. ©2000 American Institute of Physics.
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[117] Brunner, R., Stifter, T. and Marti, O. (2000). Verfahren zur Bestimmung des Abstandes einer Nahfeldsonde von einer zu untersuchenden Probeoberfläche. Germanymarti_118.pdf
Offenlegungsschrift Anmeldetag: 17. 11. 1998 Offenlegungstag 18. 5. 2000
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[118] Messerschmidt, C., Schulz, A., Rabe, J. P., Simon, A., Marti, O. and Fuhrhop, J.-H. (2000). "Formation of Stable Singularities in Mixed Monolayers of Porphyrins and Tetracosanoic Acid upon SFM Tapping." Langmuir 16(3): 1299-1305.
marti_112.pdf  
Langmuir films of tetracosanoic acid have been transferred at 10 mN/m from water to mica surfaces and were characterized by scanning force microscopy (SFM) in the tapping mode at first as a smooth monolayer. Then, upon repeated tapping cycles, many singularities appeared in form of 2.5 nm high pairs of peaks in a plane, which stretched only 1.8 nm above the mica subphase. These peaks are attributed to islands of upright-standing molecules in a layer of molecules tilted at an angle of 35. Transferring the films thus results first in a nonequilibrated film on mica, which undergoes relaxation upon tapping to a nonhomogeneous equilibrium phase. The same phenomenon was observed in films made of rigid porphyrin and tetracosanoic acid domains at 20 mN/m. The formation of fluid fatty acid structures at pressures where strong ordering prevails in pure fatty acid films was related to a reorientation in the rigid porphyrin domains after the transfer to mica. SFM phase shift images were applied to different hard and soft parts of the mixed monolayer, and scanning near-field optical microscopy was used to confirm the assignment of the porphyrin domains on the basis of their fluorescence.
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[119] Held, T., Emonin, S., Marti, O. and Hollricher, O. (2000). "Method to produce high-resolution scanning near-field optical microscope probes by beveling optical fibers." Review of Scientific Instruments 71(8): 3118-22.
marti_111.pdf  
A new two-step method to fabricate scanning near-field optical microscope (SNOM) probes with an aperture size clearly below 100 nm has been developed. For the first step, a chemical etching process is used in which an optical fiber is dipped with its acrylate jacket into hydrofluoric acid to get a suitable tapered shape of the fiber. The second step consists of beveling the etched fiber using a modified micropipette beveler to obtain a tip diameter in the nanometer range as well as a smooth surface to allow a good aluminum metallization by evaporation. By varying the beveling angle tapered shapes with different cone angles can be obtained. First transmission experiments with our probes show an optical resolution below 80 nm. In comparison to fiber tips obtained by a standard heating and pulling method, the transmission efficiency of these tips is up to three orders of magnitude higher due to the optimized tapered shape. (22 References).
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[120] Marti, O. (2000). Measurement of adhesion and pull-off forces with the AFM. Handbook of Modern Tribology. B. Bhushan, CRC.
marti_110.pdf
The key to the successful operation of an AFM(Binnig et al. 1986) in the materials sensitive regime(Burnham et al. 1989, Miyamoto et al. 1990, Mizes et al. 1991) is the measurement of the interaction forces between the tip and the sample surface. The tip would ideally consist of only one atom, which is brought in the vicinity of the sample surface. A crude estimation shows that the interaction forces between the AFM tip and the sample surface should be smaller than about 10-7N for bulk materials and preferably well below 10-9N for organic macromolecules. On the other hand there are indications that the measured values, especially of the pull-off force, are considerably off from the theoretically expected values. The reasons are manifold: The shape and size of the tip is not well known(Godowski et al. 1995, Lekka et al. 1997, RamirezAguilar et al. 1998). The composition of the surfaces of the tip and the sample might differ strongly from their bulk values. Another possibility is that the continuum mechanical models(Johnson 1992, Johnson 1996, Johnson et al. 1971, Maugis 1999) usually employed to analyze the data might fail. Pull-off force measurements(Creuzet et al. 1992, Mizes et al. 1991, Weisenhorn et al. 1992), often called adhesion measurements, are carried out since some years. The number of papers shows that the method becomes more and more popular. The theories of contact mechanics that are used in these investigations date back to the times where the only ones available test bodies were macroscopic. The remarkable precision with which these theories work in the sub-mm regime was first questioned by Stalder and Dürig (Dürig et al. 1997, Stalder et al. 1996). This paper will discuss the measurement of adhesion with the AFM and the data interpretation with respect to macroscopic theories. The discussion of limiting cases will pinpoint possible limitations.
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[121] Kröner, P., Baumeister, H., Rieger, J., Veuhoff, E., Marti, O. and Heinecke, H. (2000). "Comparison of structural and optical properties in strained GaInAsP MQW structures grown by MOVPE and MOMBE." Journal of Crystal Growth 209: 424-430.
marti_107.pdf  
The growth parameter dependence of the transition from 2D to 3D growth of GaInAsP multiple quantum well (MQW) structures up to e B "0.5% tensile-strained barriers was examined. Identical MQW structures with e W "1% compressively strained wells were grown by metal organic vapor-phase epitaxy (MOVPE) and metal organic molecular beam epitaxy (MOMBE) and characterized by photoluminescence (PL), X-ray di!raction and transmission electron microscopy. Increasing the tensile barrier strain resulted in deteriorated optical and crystalline properties beyond a critical strain limit, which depends on growth temperature. The deterioration originates from lateral layer thickness and strain modulations. Their density, amplitude and thus their e!ect on the optical MQW properties are di!erent for both rowth methods. High-quality MOMBE-grown MQW structures up to e W "2% compressive well strain and e B "0.5}1% tensile barrier strain could be achieved by inserting thin intermediate layers at each internal interface. The composition of these intermediate layers has a signi"cant e!ect on MQW material properties. ( 2000 Elsevier Science B.V. All rights reserved.
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[122] Marti, O. (2000). Raum und Zeit: eine physikalische Zeitreise. Interdisziplinäre Beiträge zu Zeit und Raum. R. Rüdel and C. Stadelhofer. Ulm, ZAWIW. 8: 78-136.
marti_106.pdf
Was ist Raum, was ist Zeit? Zur Definition der Begriffe Raum und Zeit gibt es ganz ver-schiedene Antworten. Umgangssprachlich gehen wir sehr locker mit diesen Worten um. Wer hatte noch nie "keine Zeit"? Wem ist vor allem als Kind vor dem Heiligabend die Zeit endlos lange vorgekommen oder in einem glücklichen Augenblick viel zu schnell vorbei geflogen? Genauso hängt der Begriff des Raumes in der Umgangssprache sehr stark von den Menschen die ihn gebrauchen und den kulturellen Gegebenheiten ab. Es gibt Menschen, die brauchen die Weite des flachen Landes. Nur dort fühlen sie sich frei. Es gibt andere, und dazu zählen viel-fach meine Landsleute die Schweizer, die fühlen sich im flachen Lande verloren. Die Gebor-genheit der kleinräumigen Landschaft fehlt ihnen. In der Umgangssprache haben Raum und Zeit sehr viel mit Erleben, Gefühl und Fühlen zu tun. Die physikalischen Begriffe von Raum und Zeit orientieren sich an dem was meßbar oder berechenbar ist, denn die Physik beschreibt die Natur anhand von mathematischen Modellen. Was nicht mit Mathematik beschreibbar oder was nicht meßbar ist, gehört nicht zum Gebiet der Physik. Außerhalb der meßbaren Welt macht die Physik keine Aussage zu Raum und Zeit. Dies heißt nicht, daß Aussagen über Raum und Zeit, die nicht mathematisch formulierbar sind, keine Wahrheit in sich hätten. Da die Physik ein formales Gedankengebäude ist, ist sie, wie der große Mathematiker Gödel im ersten Drittel unseres Jahrhunderts zeigen konnte, in sich selber nicht beweisbar ist. Die physikalischen Modelle der Wirklichkeit werden durch Experimente, also Messungen, getestet. Ein physikalisches Experiment kann nie beweisen, daß ein Modell wahr ist. Es kann jedoch zeigen, daß die meßbare Wirklichkeit im Widerspruch zum Modell, zur Theorie steht. In der physikalischen Umgangssprache geht man mit dieser logischen Aussage eher locker um. Wenn behauptet oder gesagt wird, daß ein Modell gezeigt wurde, heißt das, daß kein Wi-derspruch zum Modell gefunden wurde. Dieser Artikel wird im folgenden die meßbaren Ei-genschaften von Raum und Zeit diskutieren.
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[123] Brunner, R., Simon, A., Stifter, T. and Marti, O. (2000). "Modulated shear-force distance control in near field optical microscopy (NSOM)." Review of Scientific Instruments 71(3): 1466-1471.
marti_105.pdf  
(Received 29 June 1999; accepted 29 November 1999) The tip–sample distance in near-field scanning optical microscopy is typically controlled by the shear–force interaction between the laterally vibrating tip and sample. In this article, a mode of shear-force feedback is described in which an additional vertical modulation is introduced. Similar to the tapping mode applied in atomic force microscopy, the modulated shear–force technique deals with problem due to the snap to contact and therefore improves the mapping of soft and ductile materials, such as biological samples and soft polymers. The imaging properties of the modulated shear–force mode is demonstrated on structures of a soft polymer blend. Additionally, the modulated shear–force technique allows a simple comparison between effects in the optical far field and in the optical near field. ©2000 American Institute of Physics. PII: S0034-6748(00)02403-5 PACS: 07.79.Fc, 87.64.Xx
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[124] Brunner, R., Kosal, M. E., Suslick, K. S., Lamche, R., Marti, O. and White, J. O. (2000). "Near-field scanning optical microscopy of zinc-porphyrin crystals." Ultramicroscopy 84(3-4): 149-157.
marti_104.pdf  
Using a near-field scanning optical microscope (NSOM), crystals of zinc-porphyrin network materials are characterized with respect to morphology and fluorescence. Needle-shaped crystals are observed, While the topography is flat, the fluorescence intensity profile in the width direction is approximately triangular. A numerical calculation shows that differences between the topographic and optical images cannot be due to an artifact. In some needle-shaped crystals, the fluorescence emission is strongly peaked at one or both ends, possibly indicating a polar crystal structure. (14 References).
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[125] Huhn, W. E., Hollmann, F., Hild, S., Kriewall, T. and Rieger, B. (2000). "Nanostructured alkene-carbon monoxide terpolymers: New materials via a pulse-feed-polymerization technique." Macromolecular Materials Engineering 283: 115-119.
hild-x11.pdf  
The present paper reports on a novel family of ethene/CO-propene/CO-block terpolymers, with propene/CO contents up to 75 mol-%. These materials are not accessible by conventional copolymerization protocols, due to the high rate of polymerization of E/CO relative to P/CO. Therefore, a new polymerization procedure was developed that comprises a discontinuous addition of ethene/CO to an active propene/CO copolymerization reaction (pulse-feed-polymerization). This strategy affords the formation of block-copolymers with precise control over the crystallizable ECO segments, leading to excellent thermoplastic elastomers. Synthesis, structural characterization and some of the mechanical properties of this new materials are discussed.
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[126] Würthner, F., Thalacker, C., Sautter, A., Schärtl, W., Ibach, W. and Hollricher, O. (2000). "Hierarchical Self-Organization of Perylene Bisimide-Melamine Assemblies to Fluorescent Mesoscopic Superstructures." Chemistry 6(21): 3871-3886.
ibach2000.pdf  
A series of three perylene tetracarboxylic acid bisimide dyes 3 a-c bearing phenoxy substituents at the four bay positions of the perylene core were synthesized and their complexation behavior to complementary ditopic dialkyl melamines 8 a-c was investigated. Binding constants and Gibbs binding energies for the hydrogen bonds between the imide and the complementary melamine moiety have been determined in several solvents by NMR and UV/Vis titration experiments with monotopic model compounds 5 and 9. The effects of the solvent polarity and specific solvent-solute interactions on the degree of polymerization of (38)n are discussed, and a general formula to estimate the chain length of [AA-BB]n nylon-type supramolecular polymers is derived. In addition to the formation of a hydrogen-bonded supramolecular chain, - interactions were observed for perylene bisimide-melamine assemblies 3 b8 b and 3 b8 c in aliphatic solvents. The orthogonal nature of hydrogen bonding and - interactions leads to three-dimensional growth yielding large-sized aggregates already in dilute solution. On suitable substrates, densely intertwined networks of nano- to mesoscopic strands are formed which have been investigated by electron microscopy, confocal fluorescence microscopy and optical polarization microscopy. The high fluorescence and excellent photostability of these superstructures is promising for future studies on energy migration and artificial light harvesting at the nano- and mesoscopic length scale
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[127] Krotil, H.-U. and Marti, O. (1999). Dynamic Friction measurements with the AFM on polymer surfaces. Tribology 2000 - Plus. W. Bartz. Esslingen, Technische Akademie. 12: 1633-1638.
marti_109.pdf
The combination of scanning friction force microscopy (SFFM) with lock-in techniques leads to dynamic SFFM (DSFFM) and provides great advantages in friction force studies with sub-pm resolution. We present measurements on thin adsorbed organic films, on polymers (polymer blend of 75% poly(allylaminehydrochloride), PAA and 25% Poly(diallyl-dimethylammoniumchloride), PDDAC) and on mica (as a reference) The amplitude and phase response as a function of the excitation amplitude can be explained on hard surfaces by a simple static and dynamic friction model. This model aliows us to further distinguish static friction forces and kinetic friction forces in a quantitative way. Further more we demonstrate the use of these spectra to determinate the correct modulation amplitude of the excitation to achieve the optimal frictional contrasts directly. Polymer data suggest that the viscoelastic shear flow under the AFM tip is responsible for the shape of the phase and amplitude spectrum. Lastly we demonstrate that DSFFM is a useful technique for surface characterization in situations where SFFM may not be adequate.
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[128] Brunner, R., Marti, O. and Hollricher, O. (1999). "Influence of environmental conditions on shear-force distance control in near field optical microscopy." Journal of Applied Physics 86(12): 7100-7106.
marti_108.pdf  
~Received 20 January 1999; accepted for publication 7 September 1999! In our experiments we show, that a contaminating water film is very important for the shear–force distance control in near-field optical microscopy. This is demonstrated at the transition between a hydrophilic glass surface and a hydrophobic Langmuir–Blodgett film of arachidic acid at different relative humidities. This contaminating water film is one, if not the important reason for the damping of an oscillating fiber during surface approach. It is further shown, that the bulk viscosity of water alone cannot be responsible for the observed damping effect. A thickness dependent viscosity of this water film is proposed. These observations can also explain, why the shear–force distance control works on nearly all surfaces at ambient conditions, but fails to work at very low temperatures. © 1999 American Institute of Physics. @S0021-8979~99!00924-X#
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[129] Marti, O. and Hild, S. (1999). Temperature dependent surface properties of thin polystyrene films. Symposium on Microstructure and Microtribology of Polymer Surfaces, ACS Symposium Series (Boston Meeting 1998). K. J. Wahl and V. V. Tsukruk, ACS. 741: 212-226.
marti_102.pdf
Variable temperature Scanning Force Microscopy of mixed polystyrene (2000 - 100000 g/mol) and poly(methylmethacrylate) (100000 g/mol) thin films was used to probe mechanical properties such as surface stiffness and pull-off forces. Adhesion data can be explained by the molecular properties of the constituents. The adhesion of Polystyrene samples was measured by force distance curves and using the Pulsed Force Mode. It can be shown that surface tension is not the dominant part of the tip-surface interaction, but the mechani cal properties of the material will influence the measured adhesive force. Wetting of the tip by polymer molecules at higher temperatures due to increasing mobility is one possible model.Variable temperature Scanning Force Microscopy of mixed polystyrene (2000 - 100000 g/mol) and poly(methylmethacrylate) (100000 g/mol) thin films was used to probe mechanical properties such as surface stiffness and pull-off forces. Adhesion data can be explained by the molecular properties of the constituents. The adhesion of Polystyrene samples was measured by force distance curves and using the Pulsed Force Mode. It can be shown that surface tension is not the dominant part of the tip-surface interaction, but the mechani cal properties of the material will influence the measured adhesive force. Wetting of the tip by polymer molecules at higher temperatures due to increasing mobility is one possible model.
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[130] Krotil, H.-U., Stifter, T., Waschipky, H., Weishaupt, K., Hild, S. and Marti, O. (1999). "Pulsed Force Mode: a new method for the investigation of surface properties." Surface and Interface Analysis 27(5-6): 336-340.
marti_101.pdf  
Scanning force microscopy is extended by the pulsed force mode from simple imaging of topography to measuring elastic, electrostatic and adhesive sample properties. Lateral forces are virtually eliminated so that mapping of delicate samples with high resolution in air and fluids is easily possible. Scanning speed is comparable to that in contact mode. The new opportunities for scanning force microscopy given by the pulsed force mode is demonstrated in selected applications.
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[131] Krotil, H.-U., Weilandt, E., Stifter, T., Marti, O. and Hild, S. (1999). "Dynamic friction force measurement with the scanning force microscope." Surface and Interface Analysis 27(5-6): 341-347.
marti_100.pdf  
The combination of scanning friction force microscopy (SFFM) with lock-in techniques leads to dynamic scanning friction force microscopy (DSFFM) and provides great advantages in friction force studies. In the present work theoretical considerations of DSFFM are proposed to obtain quantitative friction force values from quantitative friction force values from qualitative friction force contrasts. Amplitude versus amplitude spectra and amplitude versus phase spectra are presented, obtained by measuring the amplitude and the phase signal of the (bending) scanning force contrasts by a simple method and second to determine quantitative static and kinetic friction forces. Two different polymer systems (polymer blend of 75% poly(allylaminehydrochloride) (PAA) and 25% poly(diallyldimethylammoniumchloride) (PDDAC) and a silicon surface with polyolefine contamination) served as sample systems.
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[132] Marti, O., Stifter, T., Waschipky, H., Quintus, M. and Hild, S. (1999). "Scanning Probe Microscopy of Heterogeneous Polymers." Colloids and Surfaces A: Physicochemical and Engineering Aspects 154(1-2): 65-73.
marti_93.pdf  
Adhesion, elastic and viscoelastic properties are characteristic parameters of materials. These mechanical properties of polymers show a strong dependence on the manufacturing process, the molecular weight, the temperature and the environment. It would be desirable to have tools for characterization of small samples. The scanning force microscope seems to be an ideal instrument when working towards this goal. The nanometer sized probe in contact with the sample surface can be used to measure a variety of surface properties, ranging from friction to adhesion. The measurements could be truly quantitative if one knew exactly the shape of the tip and the strength and distance dependence of the interaction forces. It is shown in this paper how the measurement modes of a scanning force microscope can be tailored to obtain quantitative data. We discuss the advantages and disadvantages of the pulsed force mode investigations using homogeneous and heterogeneous polymer samples as test objects. (30 References).
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[133] Carpick, R. W., Ogletree, D. F. and Salmeron, M. (1999). "A general equation for fitting contact area and friction vs load measurements." Colloid Interface Sci. 211: 395-400.
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[134] Held, T. and Emonin, S. (1999). Verfahren zur Herstellung einer Sonde für die optische Rasternahfeldmikroskopie. Germany, Universität UlmTo top

[135] Karl, A., Cunis, S., Gehrke, R., von Krosigk, G., Lode, U., Luzinov, I., Minko, S., Pomper, T., Senkovsky, V., Voronov, A. and Wilke, W. (1999). "Investigation of failure mechanisms in polymer composites by simultaneous measurement of ultra-small-angle scattering and acoustic emission during the deformation. I. Method." Marcel Dekker. Journal of Macromolecular Science Physics: 5-6.

Failure mechanisms in polymer composites were investigated with the method of ultra-small-angle X-ray scattering using synchrotron radiation and acoustic emission analysis simultaneously. The composites were prepared from polystyrene filled with glass beads with different coatings. The two-dimensional scattering patterns were analyzed by means of a cylinder model, while the curves of the acoustic emission signals per stress or amplitude interval were calculated and fitted by a Weibull distribution function. (14 References).
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[136] Minko, S., Karl, A., Senkovsky, V., Pomper, T., Cunis, S., Gehrke, R., von Krosigk, G., Lode, U., Luzinov, I., Voronov, A. and Wilke, W. (1999). "Investigation of failure mechanisms in polymer composites by simultaneous measurement of ultra-small-angle scattering and acoustic emission during the deformation. II. Evaluation of the interface strength." Marcel Dekker. Journal of Macromolecular Science Physics: 5-6.

The failure mechanism in polystyrene (PS) filled with glass beads was investigated with the methods of ultra-small-angle X-ray scattering (USAXS) and acoustic emission (AE) analysis simultaneously. The interface in the composites was tailored using carboxyl-terminated PS (PS-COOH). Monolayers of PSCOOH were prepared on the glass surface in a wide range of grafting densities, from single chains to a polymer brush. The layers were characterized by ellipsometry, scanning probe microscopy, and the wetting method. The morphology of the layers is in good agreement with the theoretical predictions. USAXS experiments identify submicrovoids (SMVs) at the interface in the composites even before a tensile deformation. The uniaxial loading of the specimens is followed by a debonding (dewetting) process that is identified by simultaneous increase of integral scattering intensity and AE signals. The stress of debonding is proportional to the grafting density of PS-COOH. The amplitude of the AE signals decreases as the grafting density increases. Sizes of SMVs do not depend on the draw ratio, but increase as the interface strength increases. From the analysis of all experimental data, a failure mechanism of the composites is suggested. It is proposed that the debonding stress characterizes the interface strength, while the AE amplitude gives information about the location of microdefects. (36 References).
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[137] Steinle, G., Neundorf, D., Hiller, W. and Pietralla, M. (1999). "Two-dimensional simulation of filaments in barrier discharges." Journal of Physics D Applied Physics 32(12): 1350-6.

We present a fluid model for barrier discharges in air at atmospheric pressure with spectrally resolved photonic secondary processes, implemented with general finite-element software. The results show five different discharge phases, a homogeneous and a space-charge dominated avalanche phase, a phase of dielectric charging with field enhancement due to positive ions causing streamer formation, a cathode streamer and a subsequent glow-discharge phase with a cathode-fall region. Quenching of the microdischarge occurs after a few nanoseconds by the increasing charge on the dielectric. While the capacity of the dielectric has nearly no influence on the energetic efficiency of radical production and vacuum-UV-irradiation of the dielectric, a higher voltage causes a small decrease in radical efficiency and a significant increase in the efficiency of VUV-irradiation of the dielectric. (21 References).
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[138] Hild, S., Rosa, A., Volswinkler, G. and Marti, O. (1998). PulsedForceMode - A new method for simultaneous imaging of mechanical and chemical surface properties. Bulletin of the Microscopy Society of Canada. 26: 24-25
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[139] Marti, O., Weiss, L. and Hild, S. (1998). Temperature dependent adhesive and viscoelastic poperties of polymer mixtures. 216th ACS National Meeting, August 23-27, Boston, ACS.
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[140] Drews, D., Noell, W., Ehrfeld, W., Lacher, M., Mayr, K., Marti, O., Serwatzy, C. and Abraham, M. (1998). Micromachined aperture probe for combined atomic force and near-field scanning optical microscopy (AFM/NSOM).. Materials and Device Characterization in Micromachining, Santa Clara, CA, USA, 21-22 Sept, SPIE-Int. Soc. Opt. Eng.
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[141] Miyatani, T., Okamoto, S., Rosa, A., Marti, O. and Fujihira, M. (1998). "Surface charge mapping of solid surfaces in water by pulsed-force-mode atomic force microscopy." Applied Physics A (Materials Science Processing) 66: 349-352.
marti_113.pdf  
We have studied the lateral distribution of charges on various surfaces in water by measuring the electrical double layer forces between a Si3N4 atomic force microscope (AFM) tip and the surfaces. By increasing the pH of the solution around the isoelectric point (IEP) of Si3N4 of approximately 6, the charge on the Si3N4 AFM tip was changed from positive to negative. The surface charges of the samples were also controlled by the pH of the solution in which the sample oxides were dipped. When the samples were electronically conductive, the surface charge was controlled by the electrode potentials. When the sample surface was heterogeneous in terms of the isoelectric point or point of zero charge (pzc), the surface charge was changed from one place to the other. As a heterogeneous oxide sample, a quartz plate patterned with alumina was used. The lateral charge distributions on such surfaces were mapped by pulsed-force-mode AFM. The lateral resolution of the present method was found to be approximately 20 nm.
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[142] Hild, S., Rosa, A. and Marti, O. (1998). Deformation induced changes in surface properties of polymers investigated by scanning force microscopy. Scanning Probe Microscopy of Polymers. B. D. Ratner and V. V. Tsukruk, Oxford University Press. 694: 110-128.
marti_103.pdf
In this study the possibility of combining commercial Scanning Force Microscopes (SFM) with stretching devices for the investigation of microscopic surface changes during step-wise elongation is investigated. Different types of stretching devices have been developed either for Scanning Platform-SFM or for Stand Alone-SFM Their suitability for the investigation of deformation induced surface changes is demonstrated. An uniaxially oriented polypropylene film is stretched vertically to its extrusion direction. The re-orientation of its microfibrillar structure is investigated and correlated to macroscopic structural changes determined by taking a force-elongation curve. Microtome cuts of natural rubber filled with 15 PHR carbon black are stretched. Changes in topography, local stiffness and adhesive force are simultaneously reported by using a new imaging method called Pulsed Force Mode (PFM).
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[143] Kilian, H. G., Oppermann, W., Zink, B. and Marti, O. (1998). "Relaxation of polymer molecules in networks - the extended aggregate molecules." Computational and Theoretical Polymer Science 8(1/2): 99-111.
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[144] Luzinov, I., Miko, S., Senkovsky, V., Voronov, A., Hild, S., Marti, O. and Wilke, W. (1998). "Synthesis and Behavior of the Polymer Covering on a Solid Surface. 3. Morphology and Mechanism of Formation of Grafted Polystyrene Layers on the Glass Surface." Macromolecules 31: 3945-3952.
marti_98.pdf  
ABSTRACT: Polystyrene films have been grafted by radical polymerization in situ on the surface of glass slides. The morphology of these films resulting from different grafting temperatures has been investigated by both the contact angle method and scanning probe microscopy with respect to the grafting time. At a grafting density regime where the theory proposes the existence of a homogeneous layer, the formation of island structures of grafted polymer with a size substantially higher than expected by the theory has been observed. Overshot polymer structures of large sizes are created. The amount of grafted polymer is substantially higher than that predicted from the conception of monolayer covering. The grafting layer becomes impermeable for water only at a high amount of grafted polymer, which corresponds to the multilayer structure of the coating. We suggested a mechanism for the grafting process that included at least three stages: (a) first, a brushlike polymer layer is formed; (b) subsequently, a second layer of ungrafted chains is created in the regime when excess chains are forced out from the first layer; (c) big polymer clusters, with an average size of 100-200 nm due to gel polymerization in the clusters, formed in the force out regime.
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[145] Hild, S., Krotil, U. and Marti, O. (1998). Pulsed Force Mode: A new method for characterizing thin silane films by adhesive force measurements. Tribology Issues and Opportunities in MEMS. B. Bhushan. Dordrecht, Kluwer Scientific Publishers: 247-260.
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[146] Hild, S. and Marti, O. (1998). Temperature dependent surface properties of thin polymer films. ACS Polymer Preprints. 39: 1230-1231
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[147] Hollricher, O., Brunner, R. and Marti, O. (1998). "Piezoelectrical shear-force distance control in near-field optical microscopy for biological applications." Ultramicroscopy 71: 143-147.
marti_95.pdf  
We present a piezoelectrical shear-force distance control setup for scanning near field optical microscopy. The setup is compact and tip exchange is easy. The topographical sensitivity is comparable to optical feedback systems. With an acceptable vibration amplitude 5-10 nm we obtained a topographical resolution of 5 pm/ square root Hz. Because there is no laser necessary for tip position feedback, there is no extraneous light to interfere with spectroscopic and other low-light level experiments. Our technique permits measurements of soft biological samples in aqueous solution, which opens up many possible applications of near-field optical microscopy in biology and medicine.
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[148] Barenz, J., Anger, P., Hollricher, O., Marti, O., Wachter, M., Butendeich, R. and Heinecke, H. (1998). "Spatially resolved Near Field Spectroscopy on Localized GaInAs/InP doubleheterostructures." Journal of Applied Physics 83(2): 1-7.
marti_92.pdf  
We present investigations of band-gap variations on selective grown GaxIn1-xAsyP1-y multiple quantum wells (MQW, Q1.05) using near-field optical microscopy. The MQW is excited with the near-field probe and the luminescence is collected through the same tip. By this mode, we are able to detect variation of the band gap with a lateral resolution of about 550 nm at a luminescence wavelength of 1115 nm. We show a spatial band-gap modulation near the (0-11) facet of the selective grown structures, which we suggest, is a result of a variation of the material composition. Furthermore, together with the simultaneously recorded topography, we are able to allocate a recombination path at a center wavelength of lambda =1115 nm to the intersection of the (01-1) and (11-1) vertical side facets, which are formed by interfacet diffusion during surface selective growth of the GaxIn1-xAsyP1-y MQW.
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[149] Stifter, T., Weilandt, E., Hild, S. and Marti, O. (1998). "Influence of the topography on adhesion measured by SFM." Applied Physics A 66: S597-S605.
marti_88.pdf  
Surface properties such as adhesion are influenced by the surface topography. This dependency complicates any quantitative investigation of the material constants. A simple and efficient model is used to calculate the influence of the topography on the pull of force determined by a scanning force microscope (SFM). In the model the SFM tip is represented by a sphere. The sample surface is modeled by two geometries: a step on a plane and a blister (spherical cap) on a plane. The atomic interaction between the tip and the surface is of the Lennard-Jones type. The theoretical results are compared with SFM-measurements on highly oriented pyrolytic graphite (HOPG) in electrolytic environment. The calculations are in good agreement with the measured images.
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[150] Marti, O., Barenz, J., Brunner, R., Hipp, M., Hollricher, O., Hörsch, I. and Mlynek, J. (1998). Photons and Local Probes. Nanoscale Science and Technology. N. Garcia, M. Nieto-Vesperinas and H. Rohrer. Dordrecht, Kluwer. E:348: 155-174.
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[151] Colchero, J., Meyer, E. and Marti, O. (1998). Friction on an atomic scale. Handbook of Micro/Nanotribology. B. Bhushan. Boca Raton, CRC-Press: 273-333.
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[152] Marti, O. (1998). AFM Instrumentation and Tips. Handbook of Micro/Nanotribology. B. Bhushan. Boca Raton, CRC Press: 81-144.
marti_85.pdf
The performance of AFMs and the quality of AFM images greatly depend on the instruments available and the sensors (tips) in use. To utilize a microscope to its fullest, it is necessary to know how it works and where its strong points and its weaknesses are. This chapter describes the instrumentation of force detection, of cantilevers and of the instruments themselves.
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[153] Barenz, J., Eska, A., Hollricher, O., Marti, O., Wachter, M., Schöffel, U. and Heinecke, H. (1998). "Near field luminescence measurements on GaInAsP/InP doubleheterostructures at room temperature." Applied Optics 37(1): 106-112.
marti_82.pdf  
Spatially resolved near-field luminescence spectroscopy was carried out on locally grown InP ridges, overgrown by a GaInAsP layer in metal organic molecular beam epitaxy. For free access to the quaternary layer the cleaved surface was investigated. Two different reflection scanning near-field microscopy setups were used. In the illumination mode we were able to estimate the charge-carrier diffusion in the InP. For improving the spatial resolution, measurements were also carried out in the collection mode. Here a shift of the center wavelength toward lower energy occurs near the side facets. This can be a result of a material composition gradient or of strained growth near the side facets. A second recombination channel at 1115 nm occurs at the growth-nongrowth transition. With the simultaneous recorded topography this recombination channel can be localized in the quaternary layer grown on the side of the InP ridge.
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[154] Marti, O. (1998). AFM Signals and Imaging Modes: Conventional Imaging. Handbook of Scanning Probe Microscopy. Colton, Engel, Frommer, Gaub, gewirth, Guckenberger, Heckl, Parkinson and Rabe. Chichester, UK, John Wiley and Sons: 105-109.
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[155] Anders, S. H., Eberle, R. and Pietralla, M. (1998). "Mechanical and photoelastic properties of oriented poly-4-methyl-1-pentene investigated by Brillouin spectroscopy." Journal of Materials Science 33(13): 3391-400.

The elastic constants C/sub 11/, C/sub 13/, C/sub 33/ and C/sub 44/ of oriented poly-4-methyl-1-pentane (P4M1P) films were measured with Brillouin scattering. The photoelastic constants p/sub 11/, p/sub 13/, p/sub 31/ and p/sub 33/ were measured by evaluating the integral intensities of the phonon lines. The correlation of the photoelastic constants p/sub 13/ and p/sub 31/ with the degree of stretching was determined by evaluating the relative integral intensities of the Brillouin lines with the phonon propagation vector into and perpendicular to the stress direction. The other photoelastic constants were measured by comparing the angle-dependent relative integral intensities of the transverse and longitudinal Brillouin lines. The elastic constants, as well as birefringence, were surprisingly found to be unaffected by further stretching of the sample above the necking region. The density was constant for all degrees of stretching. The photoelastic constants p/sub 11/ and p/sub 33/ showed significant variation during deformation. The results have been compared with former measurements of polypropylene (PP) by Cavanaugh and Wang. Because the elastic constants are unchanged during deformation, the modulation of the intensities is due to the variation of the photoelastic constants for this material. (31 References).
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[156] Eberle, R., Anders, S. H., Weishaupt, K. and Pietralla, M. (1998). "Anisotropic effects of the glass transition in oriented polyethylene." Europhysics Letters 43(2): 201-6.
pi1998.pdf  
The influence of orientation on the glass transition of semicrystalline polyethylene was investigated using Brillouin spectroscopy. Orientation was achieved by drawing the sample to 6.55 times its original length. The temperature range covered was 100-300 K. By performing the second logarithmic derivative of the longitudinal sound velocity vs. temperature graph the glass transition is found by a pronounced minimum. In the isotropic sample it takes place at T/sub g/=234.8+or-1.7 K. This curve nearly coincides with that found from longitudinal sound velocity in chain direction of the oriented sample. Perpendicular to the chains no effect shows up. As is discussed, thermal expansion can be ruled out as an explanation of this strong anisotropic effect. (12 References).
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[157] Luginbühl, R., Garrison, M. D., Overney, R. M., Ratner, B. D., Weiss, L. and Hild, S. (1998). Surface chemistry and elastic properties of plasma deposited fluorpolymers. Polymer Preprints (ACS). 39: 932-933
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[158] Wilke, W. (1998). "Paracrystalline distortions, inherent strains and crystallite size in polymers." Proceedings of the XVII Conference. Applied Crystallography. World Scientific.

The crystals of partially crystalline polymers are imperfect. The coherence length (crystallite size) in different crystallographic directions is in the order of some 10 nanometers and lattice distortions exist. Two types of distortions will be discussed: paracrystalline distortions and inherent strains. Paracrystalline distortions are a special type of lattice distortions, based on statistical fluctuations of the three cell edge vectors. With the assumption of statistical independence of the three coordination statistics, one arrives at the model of the ideal paracrystal. For this case an elegant mathematical formulation of the scattering theory of such a structure is possible (Hosemann). This type of distortions is found in a number of cases in polymer crystals. A structure with quasi long range order (QLRO) results. Paracrystalline distortions in polymers probably are the result of overlapping strain fields from dislocation like defects. Inherent stains develop during cooling of partially crystalline polymers, caused by inherent stresses. The inherent strains, in contrast to paracrystalline distortion, increase with decreasing temperature. Crystallite size and lattice distortions are the reasons for line broadening in the wide angle X-ray scattering patterns. The angular dependence of the broadening for the two types of distortions is different. For inherent strains the broadening is proportional to the order p of reflection (-p) for paracrystalline distortions to the square of the order (-p/sup 2/). Broadening by crystallite size is independent of p. (31 References).
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[159] Hild, S., Rosa, A., Volswinkler, G. and Marti, O. (1997). PulsedForceMode - A new method for simultaneous imaging of mechanical and chemical surface properties. Topometrix Applications Newsletter. 7: 5
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[160] Abraham, M., Ehrfeld, W., Lacher, M., Marti, O., Mayr, K., Noell, W., Güthner, P. and Barenz, J. (1997). Micromachined aperture probe tip for multifunctional scanning probe microscopy. Micro-Optical Technologies for Measurement, Sensors and Microsystems II and Optical Fiber Sensor Technologies and Applications, Munich, Germany, 18-20 June, SPIE-Int. Soc. Opt. Eng.
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[161] Miyati, T., Horii, M., Rosa, A., Fujihira, M. and Marti, O. (1997). "Mapping of electrical double-layer force between tip and sample surfaces in water by pulsed-force-mode atomic force microscopy." Applied Physics Letters 71(18): 2632-2634.
marti_94.pdf  
Pulsed-force-mode atomic force microscopy (PFM-AFM) using a cantilever with a Si3N4 tip was applied to map charge distribution on a sample surface in water. In order to confirm the applicability of the present PFM, we prepared a patterned sample by vapor deposition of Al on a quartz plate covered with silica beads, followed by oxidation of Al with O2 and removal of the beads with ultrasonication. The two different areas of Al2O3 and SiO2 had different isoelectric points and bore positive and negative charge, respectively, at pH 8.6. The lateral resolution of the present method was found to be ca. 30 nm.
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[162] Brunner, R., Hering, O., Marti, O. and Hollricher, O. (1997). "Piezoelectrical shear-force control on soft biological samples in aqeuous solution." Applied Physics Letters 71: 3628-3639.
marti_91.pdf  
In order to apply scanning near-field optical microscopy to life science, it is essential to have an accurate distance feedback that also works on soft biological samples in liquids. In this letter, the authors report measurements of neuron cells in aqueous solution using an advanced piezoelectrical shear-force detection setup. Simultaneously obtained topographical and fluorescence images are presented, demonstrating a resolution below 100 nm in the optical image. The influence of the water level on the shear-force signal and the interaction between near-field probe and soft organic samples are discussed. Stable feedback in fluids is obtained with tip-sample interaction forces below 100 pN.
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[163] Brunner, R., Bietsch, A., Hollricher, O., Marti, O. and Lambacher, A. (1997). "Application of a near-field optical microscope to investigate the fluorescence energy transfer between chromophores embedded in Langmuir-Blodgett films." Surface and Interface Analysis 25(7-8): 492.
marti_90.pdf  
Scanning near-field optical microscopy (SNOM) was used to investigate the fluorescence energy transfer between a monomolecular film of monomethin oxacyanine and a layer of monomethin thiacyanine in arachidic acid, The donor and acceptor chromophores are fixed in Langmuir-Blodgett (LB) films, spaced by the identical chains of the arachidic acid and dye, respectively. The length of these hydrophobic chains guarantees a fixed distance between the different kinds of chromophores. The dye molecules are oriented parallel to the plane of the LB film, In the LB layer assembly, a step was prepared to separate two different regions. One area contains both kinds of chromphores, whereas in the other area only the donor dyes are present, We used the SNOM technique because of the possibility to measure simultaneously the fluorescence behaviour and topographical structure. (C) 1997 by John Wiley & Sons, Ltd.
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[164] Müller, T., Lohrmann, M., Kässer, T., Marti, O., Mlynek, J. and Krausch, G. (1997). "Frictional force between a sharp asperity and a surface step." Physical Review Letters 79: 5666-5669.
marti_89.pdf  
We report a detailed study of the frictional force between the tip of a scanning force microscope and a step on a crystalline surface. Experiments on surfaces of freshly cleaved graphite reveal different contributions to the lateral force at steps with distinctly different dependencies on normal load and scan direction. The different contributions can be attributed to topography-induced tip twisting and an increased dissipative force due to the Schwoebel barrier at the steps. The latter contribution is strongly reduced when near-surface step dislocations are imaged.
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[165] Rosa-Zeiser, A., Weilandt, E., Hild, S. and Marti, O. (1997). "The simultaneous measurement of viscoelastic, electrostatic and adhesive properties by SFM: pulsed force mode operation." Measurement Science and Technology 8: 1333-1338.
marti_83.pdf  
We describe the pulsed-force mode, a new measuring mode for the scanning force microscope to image elastic, electrostatic and adhesive properties simultaneously with topography. The pulsed-force mode reduces lateral shear forces between the tip and the sample. Even very delicate samples can be mapped at high lateral resolution with full control over the force applied to the sample. The achieved scanning speed is comparable to that in contact-mode operation. The pulsed-force mode electronics can easily be added to many microscopes without much alteration of the original set-up. No change of the data acquisition software or of the feedback circuit is necessary.
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[166] Rosa, A., Kilian, H. G., Hild, S. and Marti, O. (1997). Pulsed Scanning Force Microscopy on the Surface of Linear Deformed, Filler Loaded Rubber - a New Method of Investigation. Intern. Rubber Conference 1997.
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[167] Brunner, R., Bietsch, A., Hollricher, O. and Marti, O. (1997). "Distance Control in Near-Field Optical Microscopy with electrical shear force detection suitable for imaging in liquids." Review of Scientific Instruments 68(4): 1769-1772.
marti_79.pdf  
We introduce an improved piezoelectric shear-force feedback system for tip-sample distance control in a scanning near-field optical microscope. A tapered glass fiber is glued into a metal tube and both are integrated in a mounting, sandwiched between two piezosegments. One of the piezoelements excites the fiber tip at mechanical resonance while the other one is used for detection. During surface approach the fiber resonance is damped by shear forces, which is registered by the second piezoelement and used for distance control. The main attractions of this setup are its simplicity, its compactness, and the lack of disturbing light sources. The fiber is easy accessible and tip exchange is simple. With an acceptable fiber amplitude of 5-10 nm (peak to peak) we obtained a topographical resolution of 5 pm/ square root Hz. The geometry also allows the measurement of samples covered with a few millimeters of liquid, which is important for applications in biology and medicine.
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[168] Noell, W., Abraham, M., Mayr, K., Ruf, A., Barenz, J., Hollricher, O., Marti, O. and Güthner, P. (1997). "Micromachined aperture probe tip for multifunctional scanning probe microscopy." Applied Physics Letters 70(10): 1236-1238.
marti_78.pdf  
A novel micromachined aperture tip has been developed for near-field scanning optical microscopy. The advantages of the new probe over commonly used fiber probes are illustrated. The aperture tip is fabricated in a reliable batch process which has the potential for implementation in micromachining processes of scanning probe microscopy sensors and therefore leads to new types of multifunctional probes. For evaluation purposes, the tip was attached to an optical fiber by a microassembly setup and subsequently installed in a near-held scanning optical microscope. First measurements of topographical and optical near-held patterns demonstrate the proper performance of the hybrid probe. (C) 1997 American Institute of Physics.
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[169] Marti, O., Hild, S., Staud, J., Rosa, A. and Zink, B. (1997). Nanomechanical interactions of scanning force microscope tips with polymer surfaces. Micro/Nanotribology and its applications. B. Bhushan. Dordrecht, Kluwer Scientific Publishers. E:330: 455-465.
marti_75.pdf
PMMA-surfaces have been investigated by scanning force microscopy as a function of temperature and imaging conditions. A stand-alone type scanning force microscope was employed together with a heating stage to investigate a model polymer substance, PMMA, as a function of temperature. Contact mode imaging induced wavy structures at higher temperatures, whereas intermittent imaging in the pulsed force mode showed negligible interactions.
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[170] Weilandt, E., Zink, B., Stifter, T. and Marti, O. (1997). Nanotribology in electrolytic environments. Micro/Nanotribology and its Applications. B. Bhushan. Dordrecht, Kluwer Academic Publishers: 283-297.
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[171] Marti, O. (1997). Instrumentation for Scanning Force Microscopy and Friction Force Microscopy. Macro- and Microtribology. B. Bhushan. Dordrecht, Kluwer Academic Publishers. 330: 455-465.
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[172] Spatz, J. P., Sheiko, S., Möller, M., Winkler, R. G., Reineker, P. and Marti, O. (1997). "Tapping Scanning Force Microscopy in Air - Theory and Experiment." Langmuir 13: 4699-4703.
marti_68.pdf  
Ultrathin layers of micelles of a diblock copolymer with a polystyrene corona and a poly(2-vinylpyridine) core have been studied by tapping scanning force microscopy in air, probing the surface with varying forces depending on the setpoint of the probe and the tapping frequency. The compliance of the core of the micelles was varied by neutralization of the pyridine groups with HAuCl4 and incorporation of small particles. The apparent deformation of the globular micelles was compared with a simple model describing the probe as a forced oscillator which changes its effective spring constant depending on the direct contact with the surface. Consistent with the experiment, the model shows that the deformation and the shift in phase are minimized by tapping on the low-frequency side of the noncontact cantilever resonance.
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[173] Marti, O., Weilandt, E., Rosa, A., Staud, J., Zink, B., Hörsch, I., Kusche, R., Kirschenhofer, O. and Hollricher, O. (1997). SFFM and SNOM of Heterogeneous Materials. Chemical, Structural and Electronic Analysis of Heterogeneous Surfaces on Nanometer Scale. R. Rosei. Dordrecht, Kluwer Academic Publishers. 333: 25-41.
marti_63.pdf
It is often difficult to characterize and distinguish heterogeneous materials with domain sizes below 1 micrometer. The range between 1 nm and 1 µm lies in the crossover region where light scattering is applicable to the upper wavelength range and where x-ray and neutron scattering is strongest for the lower wavelength end. In addition the scattering methods require careful experimental procedures for a reconstruction of the real space structure. Scanning probe methods do provide a direct access to the surface properties in the range of interest. They are complementary to the recently developed x-ray imaging methods. In this paper we discuss the application of the scanning force and friction microscope and the near-field optical microscope to heterogeneous surfaces. The image formation process in both microscopes is different: the scanning force and friction microscope probes the nanomechanical properties of sample surfaces. The near-field optical microscope on the other hand measures the reflectivity, absorption or the fluorescence near the sample surface. As an application we discuss the imaging of polymer surfaces.
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[174] Anders, S. H., Hrbecek, H. H. and Pietralla, M. (1997). "Longitudinal sound velocity in uniaxially stretched rubberlike polymers." Journal of Polymer Science Part B Polymer Physics 35(11): 1661-76.

We present a new method to interpret data obtained by Brillouin-scattering from oriented networks. Because in rubberlike samples the transverse sound waves are normally not observable, it is not possible to extract the complete set of elastic constants. We will show that by combining a model of the orientation process with the lattice-model from Kondo and Igarashi, force constants can be determined from the sound velocities. These force constants can be discussed in terms of molecular conformations and interactions. The anisotropic hypersound velocity was measured in polyurethane- and polysiloxane networks. With the help of the combined orientation-lattice-model evaluation, different kinds of forces can be distinguished. By comparing the force constants with Raman- or infrared spectroscopic data, information about the conformation of the polymer chains can be determined. The effective force constants of the segments are an order of magnitude lower than that of the polymer main chains and the ratio of force constants along and between the 5:1. (39 References).
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[175] Brunner, R., Gall, S., Wilke, W. and Zrinyi, M. (1997). "A dynamic light scattering study on aggregation of rodlike colloidal particles." Physica A 239(4): 477-85.

The kinetics of aggregation of rodlike iron(III)hydroxide colloids in aqueous solution have been investigated by dynamic light scattering. KNO/sub 3/ and K/sub 2/SO/sub 4/ electrolytes were used in different concentrations as controllers for the aggregation kinetics. The experimental results of the cluster growth were fitted in the fast regime to the diffusion limited aggregation (DLA) and are characterized by a power law with a fractal dimension d/sub f/=1.71. Clearly, the slow aggregation shows the exponential kinetics of the reaction limited aggregation (RLA). In the growing curves of the colloid clusters, a transition to a very fast aggregation kinetic was observed. The transition occured at a typical aggregate size which was crucially dependent on the colloid concentration. This was taken as an evidence for a percolation process. (12 References).
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[176] Endres, A., Lode, U., Von Krosigk, G., Bark, M., Cunis, S., Gehrke, R. and Wilke, W. (1997). "X-ray absolute intensity measurement at HASYLAB ultrasmall angle X-ray scattering beamline BW4." Review of Scientific Instruments 68(11): 4009-13.

In order to obtain small angle scattering intensities in absolute units, measurements of the incident beam intensity and the intensity transmitted through the sample are required. For this purpose the scattering intensity of a calibrated polyethylene (LUPOLEN) standard is used. For the determination of the absolute photon flux and the correction of the scattering patterns obtained with a two dimensional position sensitive detector we use the detector response function. A set of data measured subsequently at the standard and at a given sample can be evaluated in a program that calculates a pattern in absolute units corrected by means of the detector response. This program also calculates the absolute photon flux, determines automatically the center coordinates of the incident beam, and calculates the scattering vectors that belong to the different positions on the detector. (15 References).
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[177] Griesinger, A., Hurler, W. and Pietralla, M. (1997). "A photothermal method with step heating for measuring the thermal diffusivity of anisotropic solids." International Journal of Heat & Mass Transfer 40(13): 3049-58.

A pure radiative method is presented for measuring the directionally-dependent thermal diffusivities of anisotropic solids, especially of free-standing films. A real point and line source are realized by a focused laser beam. Both configurations allow measurements of the anisotropic thermal diffusivity. Because of the smaller power density applied for the line source, this method is very suited for thermic sensitive films. Virtual image sources are used to account for the boundary conditions of a rectangular slab. The temperature vs time curves are recorded by infrared radiation using an InSb-detector. They are fitted to the solution for a constant heat source switched on at time zero (step heating) disregarding the prefactor. Thus, there is no need to know the absorption coefficient or the absolute temperature rise of the sample. The influence of sample dimensions and of radiative losses is investigated. For sufficiently thin samples a two-dimensional treatment is suited. Extrapolating the diffusivities determined in different time spans to zero heating time excludes radiation losses. A comparison to results from steady-state methods for well-defined samples confirm the reliability of the method. Representative results on highly oriented polymers are presented. (13 References).
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[178] Kilian, H. G., Zink, B. and Metzler, R. (1997). "Aggregate model of liquids." Journal of Chemical Physics 107(20): 8697-705.

Atomic-force pictures reveal a heterogeneous microstructure at the surface of glassy layers which should be similar to one of the many equivalent microstructures a liquid is running through. These microstructures are described with the aid of a kinetic model of reversible aggregation which goes back to formulations as used in the description of living polymerization or aggregation of polymers in solution. Aggregates are considered as dynamic subsystems wherein collective modes of motions are excited. Fluctuations of the aggregates, densely packed in a disordered pattern, leads to a broad size distribution which happens to be controlled by Boltzmann's factor. The disordered structure within the aggregates themselves is optimized, reduced aggregate energy and entropy should be equal. Symmetries are deduced which elucidate many universal properties of the dynamic microstructure of liquids. Thermodynamic properties like the specific heats of aggregation in liquids or the dependence of the glass transition of homologues of linear atactic polystyrene are consistently described. (52 References).
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[179] Kraus, R., Wilke, W., Zhuk, A., Luzinov, I., Minko, S. and Voronov, A. (1997). "Investigation of debonding processes in particle-filled polymer materials by acoustic emission. I. Acoustic emission and debonding stress." Journal of Materials Science 32(16): 4397-403.

Debonding processes in model composites under tensile deformation were investigated by acoustic emission analysis. The composites were prepared from epoxy and polyethylene matrix filled with glass beads of various sizes and with different coatings. The detected acoustic emission signals were identified as debonding processes at the filler-matrix interphase, and are discussed as a rupture process an the basis of the Weibull probability distribution function. For the model composites, the effect of the filler size is discussed using a theory based on Griffith's criterion of rupture. (13 References).
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[180] Kraus, R., Wilke, W., Zhuk, A., Luzinov, I., Minko, S. and Voronov, A. (1997). "Investigation of debonding processes in particle-filled polymer materials by acoustic emission. II. Acoustic emission amplitude and energy release by debonding." Journal of Materials Science 32(16): 4405-10.

A theoretical description of the debonding process is presented by using Griffith's criterion of rupture, that is applied to the balance of free energy during the debonding of a spherical filler particle from the polymer matrix. Debonding processes in model composites prepared from epoxy and polyethylene matrix filled with glass beads of various sizes have been investigated by acoustic emission analysis. The amplitude distribution for all AE events at the debonding stress was calculated and fitted by a Weibull distribution function. By comparing the results of debonding stress with the measured amplitudes, the influence of the different filler coatings on the energy balance of debonding can be discussed on the basis of the Griffith theory. (11 References).
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[181] Pietralla, M., Hotz, R., Engst, T. and Siems, R. (1997). "Chain direction elastic modulus of PE crystal and interlamellar force constant of n-alkane crystals from RAMAN measurements." Journal of Polymer Science Part B Polymer Physics 35(1): 47-57.

Spectroscopic data can deliver force constants only if the exact chain conformation is known. For the longitudinal acoustic modes (LAM), however, simple linear chain models can be used to yield the effective longitudinal chain modulus from spectroscopic data of oligomer crystals. The model of p-coupled linear chain molecules with N masses and only nearest neighbor interactions was used to investigate the longitudinal acoustic modes with s nodes. The frequencies plotted versus s/N fall onto different branches for differents. The intermolecular coupling and the heavier endmasses shift the LAM branches to higher and lower frequencies, respectively. There exists a value x/sub 0/ depending on the masses and force constants, where the branches cut the dispersion curve of the infinite molecule. For s/N>or=x/sub 0/ the effect of endmasses dominates. Low-frequency RAMAN spectra of n-alkanes (N=20, ..., 40 C atoms) were recorded and analyzed. The LAM1 branch runs clearly above a smooth fit through all other LAM data and the origin. This fit approximates to first order the dispersion curve of the infinite PE molecule in an ideal crystal. Its curvature exceeds that of the dispersion curve of the simple linear chain, but is somewhat smaller than that of the dispersion curve of the planar zig-zag chain with rigid bonds. The slope at the origin yields the limiting elastic modulus E/sub c/=315 GPa in chain direction of crystalline polyethylene. From our measurements on n-alkanes we obtained the frequency shift of LAM1 due to the interlayer coupling and the heavier endmasses. (22 References).
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[182] Weishaupt, K., Anders, S. H., Eberle, R. G. and Pietralla, M. (1997). "A new design for a versatile Fabry-Perot interferometer for Brillouin spectroscopy." Review of Scientific Instruments 68(11): 3996-4000.

We present a new design of a Fabry-Perot interferometer for Brillouin spectroscopy. Emphasis is placed on a quick change of the free spectral range without losing alignment, the possibility of switching the multipass arrangement from 3 to 5 pass and back, and finally on a simple and inexpensive construction. Besides this the new interferometer shows very good long term stability and is easy to handle. These features were not available before in this combination. The performance of the instrument will be demonstrated. (17 References).
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[183] Zrinyi, M., Barsi, L., Szabo, D. and Kilian, H. G. (1997). "Direct observation of abrupt shape transition in ferrogels induced by nonuniform magnetic field." Journal of Chemical Physics 106(13): 5685-92.

Unidirectional elongation of magnetic field sensitive polymer gels, called ferrogels, have been studied. In ferrogels, finely distributed colloidal particles having superparamagnetic behavior are incorporated into a swollen network. These particles couple the shape of the gel to the nonuniform magnetic field. Shape distortion occurs instantaneously and disappears when the external field is removed. A discontinuous elongation and contraction in response to infinite-small change in the external magnetic field has been observed and a theoretical interpretation based on coupled magnetic and rubber elastic properties is provided. (0 References).
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[184] Kamp, M., Mayer, M., Pelzmann, A., Menzel, S., Chung, H. Y. A., Sternschulte, H., Marti, O. and Ebeling, K. J. (1996). "NH3 as nitrogen source in MBE growth of GaN." Mat. Res. Soc. Symp. Proc. 395: 135-140.

We report on the growth of GaN in GSMBE using NH3 as nitrogen source. Special focus will be on the NH3 cracking, where we applied an On Surface Cracking technique (OSC). Using OSC we achieve photoluminescence linewidths as narrow as 5.5 meV (5 K) and mobilities of 220 cm2/Vs at room temperature. (5 References).
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[185] Hild, S. and Marti, O. (1996). Structural changes during stretching uniaxially oriented polypropylene film investigated by AFM. Polymer Preprints. 37.2: 569-570
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[186] Marti, O. (1996). "Transversale Moden in Laserdioden." Physikalische Blätter 52: 1132-1133.
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[187] Colchero, J., Baró, A. M. and Marti, O. (1996). "Energy dissipation in scanning force microscopy - friction on an atomic scale." Tribology Letters 2: 327-343.
marti_77.pdf  
Stick-slip behaviour for a typical scanning force microscope setup operated in the wearless friction regime is modelled. Not only the deflection of the cantilever but also the local elastic deformation of tip and sample are taken into account. The combined effect of macroscopic spring and microscopic elastic deformation is a key feature to the scanning motion of the tip. Within this model, energy dissipation arises naturally due to mechanical instabilities either of the macroscopic cantilever or of the microscopic tip sample contact. Our model reproduces all features of atomically resolved friction loops, which can be calculated from interatomic potentials. Moreover, a general scheme is introduced which allows the exact response of the tip-sample system to be calculated from the different interacting potentials. (20 References).
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[188] Marti, O. and Mlynek, J. (1996). "Friction Microscopy as a New Way - Novel Methods involve Incursion into the Nano Range." German Research 3/96: 28-29.
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[189] Rosa, A., Hild, S. and Marti, O. (1996). Deformation induced changes in surface properties of natural rubber. ACS Polymer Preprints. 37.2: 616-617
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[190] Marti, O. and Mlynek, J. (1996). "Reibungsmikroskopie als neuer Weg: Vorstoss in die Nanowelt." DFG-Nachrichten 1/96: 11-12.
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[191] Winkler, R. G., Spatz, J. P., Sheiko, S., Moller, M., Reineker, P. and Marti, O. (1996). "Imaging material properties by resonant tapping-force microscopy: A model investigation." Physical Review B Condensed Matter 54(12): 8908-8912.
marti_69.pdf  
The interaction of a cantilever performing a forced oscillation with a sample in a tapping-mode scanning force microscope is investigated within a simple model. The tip together with the cantilever is modeled as a periodically driven, damped harmonic oscillator. The viscoelastic sample is described by a friction force acting on the tip while it is in contact and a harmonic potential. The penetration of the probe and the phase shift of the oscillator due to contact with the sample are calculated for various sample parameters. In particular, an approximate solution of the model equations for the phase shift is presented. Moreover, a relation between the elastic constant of the model and the elastic modulus of a material is presented.
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[192] Hörsch, I., Kusche, R., Marti, O., Weigl, B. and Ebeling, K. J. (1996). "Spectrally resolved near-field mode imaging of vertical cavity semiconductor lasers." Journal of Applied Physics 79(8 Part 1): 3831-3834.
marti_67.pdf  
The transversal mode properties of vertical cavity surface emitting lasers (VCSELs) are studied by spectrally resolved scanning near-field optical microscopy. In contrast to classical optical microscopy techniques, our method is able to simultaneously decompose lasing transversal modes by their wavelength with lateral superresolution. As the tip-sample distance is controlled by the well-established shear-force detection, additional topographical information showing the surface structure of the laser is provided. Therefore, near-field spectroscopy allows the detailed analysis of the spatial light distribution emitted by the laser
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[193] Barenz, J., Hollricher, O. and Marti, O. (1996). "An easy-to-use non-optical shear-force distance control for near-field optical microscopes." Review of Scientific Instruments 67(5): 1912-1916.
marti_66.pdf  
We present an easy-to-use non-optical shear-force detection system for tip-sample distance control in scanning near-field optical microscopes. The fibre tip is fixed in a four-segmented piezo-tube by a polymer, Polyisobutylene, which couples the tip stiffly to the piezo at frequencies of 10 kHz or more at room temperature. One segment of the piezo-tube excites the fibre tip in resonance, while the other three segments detect the tip vibration in the manner of a piezo-microphone. When the tip is damped by shear forces the induced voltage at the three segments changes and can easily be detected with a lock-in amplifier. Further our method allows a fast and reproducible tip exchange with minor adjustments of mechanical ol electrical components. We demonstrate the performance of our distance control on a holographically fabricated line pattern with 417 nm lattice spacing and 10 nm height. A height resolution of better than 1 nm is demonstrated. (C) 1996 American Institute of Physics Article
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[194] Müller, T., Kässer, T., Labardi, M., Lux-Steiner, M., Marti, O., Mlynek, J. and Krausch, G. (1996). "Scanning force and friction microscopy at highly oriented polycrystalline graphite and CuP2(100) surfaces in ultrahigh vacuum." Journal of Vacuum Science & Technology B 14(2): 1296-1301.
marti_64.pdf  
N1 - We present a novel scanning force and friction microscope for applications in ultrahigh vacuum (UHV) using the optical beam deflection method for detection. All optical components are positioned on the air side enabling a simple way of adjustment, the possibility of good decoupling of topography and lateral signal, and the absolute estimation of lateral force values, We demonstrate lateral atomic resolution on mica surfaces freshly cleaved in UHV. As model systems, we investigate the complex CuP2(100) surface on the unit cell level which exhibits a wide range of atomic stick-slip phenomena. In addition, first results on the friction behavior at step edges on highly oriented polycrystalline graphite surfaces are presented.
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[195] Hild, S., Gutmannsbauer, W., Luthi, R., Fuhrmann, J. and Guntherodt, H. J. (1996). "A nanoscopic view of structure and deformation of hard elastic polypropylene with scanning force microscopy." Journal of Polymer Science Part B Polymer Physics 34(12): 1953-9.

Scanning force microscopy (SFM) was used to visualize the surface of hard elastic polypropylene (HEPP) film. The surface morphology of unstrained HEPP shows crystalline and noncrystalline rows oriented parallel to the extrusion direction. The crystalline rows are composed of lamellar blocks. The dimensions of crystalline and noncrystalline regions are determined. The structural surface changes induced by stepwise elongation of the film with a home-built stretching device are documented by SFM. Stretching of HEPP perpendicular to the extrusion direction causes cracks advancing through several crystalline rows. During elongation parallel to the extrusion direction the separation of adjacent lamellae by their translatory displacement occurs. Deformation-induced structural changes of HEPP on the nanometer scale are compared with proposed deformation models. Nanostructural changes are correlated with characteristic variations in the force-elongation curve. (14 References).
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[196] Krbecek, H. H., Kupisch, W. and Pietralla, M. (1996). "A new Brillouin scattering analysis of high frequency relaxations in liquids demonstrated at the hypersound relaxation of PPG." Polymer 37(16): 3483-91.

We present a new method to analyse data obtained by Brillouin scattering. Using two scattering geometries simultaneously and measuring separately the refractive index n(T) we can determine the logarithmic derivative delta lgM'( omega ,T)/ delta lg omega =Q/sub M/ and thus are able to characterize unambiguously the dominant fast processes by high precision frequency shift measurements. For a sufficient narrow relaxation time distribution the imaginary part M"( omega ,T) of the complex modulus M( omega ,T)=M'( omega ,T)+iM"( omega ,T) can be derived. Analysing data of poly(propylene glycol) with M/sub w/=1000 (PPG 1000) we find the fastest process to show Arrhenius behaviour. Using published data from impulsive surface scattering we can finally deconvolute a set of three different processes: two exhibiting Arrhenius behaviour and one showing Vogel-Fulcher-Tammann behaviour. These three processes describe the data to a high accuracy and are tentatively assigned to molecular motions. At high frequencies the relaxation time distribution observed narrows to a single relaxation time. In the light of these results it seems questionable to use linewidth data from Brillouin scattering experiments to determine the width of the relaxation process. From the present work we believe the experiments with surface acoustic waves to be the most effective since they can be coupled with Brillouin scattering experiments. (31 References).
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[197] Kruger, J. K., Bohn, K. P., Pietralla, M. and Schreiber, J. (1996). "Anharmonic properties of fragile and strong liquids: temperature dependence of the mode Gruneisen parameter." Journal of Physics Condensed Matter 8(50): 10863-74.

Brillouin spectroscopy, dilatometry and calorimetry results have been used to investigate the temperature anomaly of the mode and thermal Gruneisen parameters around the glass transition of the fragile liquid poly(vinyl acetate). These results are compared with those of the strong liquids C/sub 17/H/sub 36/, C/sub 24/H/sub 50/ and 4-cyano-4-6-alkylbiphenyl. (30 References).
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[198] Nurdin, N., Weilandt, E., Textor, M., Taborelli, M., Spencer, N. D. and Descouts, P. (1996). "Reduced frictional resistance of polyurethane catheder by means of a surface coating procedure." Journal of Applied Polymer Science 61: 1939-1948.
nurdin_1.pdf  
Polyurethane and poly(viny1 pyrrolidone) (PVP)-coated polyurethane catheter surfaces were characterized by time of flight secondary ion mass spectrometry (TOF-SIMS) and were compared in terms of wettability and adhesion and friction properties by scanning force microscopy (SFM). Using TOF-SIMS, the presence of hard segments in the first layers of the polyurethane catheter were shown, and the presence of a PVP coating on the modified catheters was clearly identified. The PVP coating induced a hydrophilic surface after immersion of the catheters in water for several hours. When SFM experiments were carried out in water, the adhesive force developed between the PVP-ccated surface and the tip became immeasurably small. Tribometric measurements along a 500-nm scan line quantified friction coefficients of 0.05 for the coated catheter and 0.50 for the native poly-urethane catheter. The PVP coating on catheters provided smooth, soft, and nonadhesive surface properties, which would minimize difficulties during their insertion into the vessels of the patient. 0 1996 ,John Wiley & Sons, Inc.
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[199] Pietralla, M., Mayr, P. and Weishaupt, K. (1996). "The dependence of the glass temperature of two polymeric glasses on energy density tested by pressure variations." Journal of Non Crystalline Solids 195: 1-2.

A recently discussed relation between thermal energy at the glass transition temperature and the kinetic energy of sound waves has been examined. The transition temperature and the sound velocity of the polymeric glasses polycarbonate and poly(methyl-methacrylate) have been changed by pressure variations up to 600 MPa. The result fits to the proposed relation. The masses involved are found to be the at least partly independent mobile parts of the complex molecules. (7 References).
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[200] Marti, O. and Möller, R., Eds. (1995). Photons and Local Probes. NATO ASI Series. Dordrecht, Kluwer Scientific Publishers.

[201] Weilandt, E., Menck, A. and Marti, O. (1995). "Friction studies at steps with friction force microscopy." Surf.Interface Anal. 23: 428-430.
marti_61.pdf  
In this study we investigated the contrast of lateral force at highly oriented pyrolytic graphite steps in an electrolytic environment with a scanning force and friction microscope. A characteristic enhancement of lateral force was visible. Steps were imaged with and without electrochemical potential control whereby a change of friction with potential could be observed. The behaviour of lateral force at the steps indicated that tbe observed contrast enhancement must be a real friction effect and is not caused solely by the topography
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[202] Marti, O. and Krausch, G. (1995). "Nahfeldoptik mit atomarer Auflösung?" Physikalische Blätter 51: 493-496.
marti_60.pdf  
Nahfeld-optische Techniken werden intensiv erforscht und verbessert, um eine wesentlich höher ortsauflösende optische Mikroskopie zu erhalten. Anwendungen der nahfeld-optischen Mikroskopie reichen von festkörperphysikalischen Problemen bei tiefen Temperaturen über Untersuchungen an Halbleiterproben bis zu biologischen Fragestellungen. Eine ungelöste Frage ist dabei die maximale mögliche Auflösung. In diesem Beitrag möchten wir an ausgewählten Beispielen aufzeigen, welche Konzepte verfolgt werden. Ihre Stärken und Schwächen werden kritisch analysiert und eine Wertung des Entwicklungspotentials wird versucht.
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[203] Hörsch, I., Kusche, R., Hollricher, O., Kirschenhofer, O., Marti, O., Sieber, R., Krausch, G. and Mlynek, J. (1995). A Stand-Alone Scanning near-Field Optical Microscope. Photons and Local Probes. O. Marti and R. Möller. Dordrecht Boston London, Kluwer Academic Publishers. E 300: 139-144.
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[204] Hipp, M., Mertz, J., Mlynek, J. and Marti, O. (1995). Optical Near-Field Imaging by Force Microscopy. Photons and Local Probes. O. Marti and R. Möller. Dordrecht, Netherlands, Kluwer Academic Publishers. E 300: 109-122.
marti_58.pdf
A scanning force microscope (SFM) is used to detect near field light by a mechanism based on optical modulation of the image force between a semiconducting probe tip and a glass surface. The modulation stems from a phenomenon called surface photo-voltage (SPV). The performance of the mechanism for near-field microscopy is demonstrated by imaging a standing evanescent light wave and profiling structured samples. The lateral resolution is found to be better 110 nm (sub-wavelength) and a representative minimum detectable power is 0.1 pW/ square root Hz in air. A simple theoretical model is described which yields a good agreement with experimental results. As a first application of this technique imaging results on light induced space charge gratings in photorefractive materials are presented.
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[205] Spatz, J. P., Sheiko, S., Möller, M., Winkler, R. G., Reineker, P. and Marti, O. (1995). "Forces affecting the substrate in tapping mode." Nanotechnology 6: 40-44.
marti_57.pdf  
We propose a simple model to describe the interaction of a forced cantilever oscillation with a specimen in a tapping-mode scanning force microscope experiment in order to make a rough estimation of the forces affecting the surface with each touch down of the tip. Assuming weak damping of the cantilever (quality factor of the cantilever between 100 and 1000) and of the surface, we can estimate the forces to be in the range of those in the contact mode. These forces can vary by orders of magnitude, e.g. 10-6 to 10-11 N. To reduce the interaction force we suggest scanning on the low-frequency side of the resonance frequency of the non-contact cantilever oscillation. Increasing the difference of phase between the non-contact oscillation of the cantilever in air and the oscillation during contact introduces strong variations of the force. The improvement in resolution which can be achieved for soft samples by using the tapping-mode system results from the elimination of shear forces and the possibility of minimizing the force on the surface by varying the set-point of the scanning amplitude. Forces on the substrate will be enhanced by a large substrate stiffness.
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[206] Straub, W., Bruder, F., Brenn, R., Krausch, G., Bielefeldt, H., Kirsch, A., Marti, O., Mlynek, J. and Marko, J. F. (1995). "Transient wetting and 2D spinodal decomposition in a binary polymer blend." Europhysics Letters 29: 353-358.
marti_55.pdf  
We have used ion beam analysis and scanning near-field optical microscopy to characterize the three-dimensional domain structure of a thin film of a phase-separating polymer mixture. In the initially mixed film, there first occurs coverage of one of its surfaces by an unbroken layer of one phase; between this <> surface and the substrate, layers of domains form. Eventually, the layered domain structure becomes unstable, and a transformation occurs to the equilibrium wetting state where both phases are in contact with both surfaces, causing a phase separation to be purely two-dimensional at later times. During this "transient wetting" process, lateral and vertical domain sizes grow with time as t1/3 independent of the dimensionality of the domains.
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[207] Colchero, J., Marti, O. and Mlynek, J. (1995). Friction on an atomic scale. Forces in Scanning Probe Methods. H. J. Güntherodt, D. Anselmetti and E. Meyer. Dordrecht, Kluwer. E:286: 345-352.
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[208] Weilandt, E., Menck, A., Binggeli, M. and Marti, O. (1995). Friction Force Measurements on Graphite Steps under Potential Control. Electrochemistry. A. A. Gewirth and H. Siegenthaler. Doordrecht, Kluwer. E:288: 307-315.
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[209] Niedermann, P., Burger, J., Binggeli, M., Christoph, R., Hintermann, H. E. and Marti, O. (1995). A Scanning Force and friction Microscope. Ultimate Limits of Fabrication & Measurement, Proceedings of the NATO Advanced Research Workshop on "Ultimate Limits of Fabrication & Measurement", Cambridge, April 1-3 (1994). M. E. Welland and J. K. Gimzewski, Kluwer Academic Publishers. 292.
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[210] Burger, J., Binggeli, M., Christoph, R., Hintermann, H. E. and Marti, O. (1995). Nanotribology and chemical sensitivity on a nanometer scale. H. J. Güntherodt, D. Anselmetti and E. Meyer. Dordrecht, Kluwer. 286: 325-330.
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[211] Marti, O. and Colchero, J. (1995). Scanning Probe Microscopy Instrumentation. Forces in Scanning Probe Methods. H. J. Güntherodt, D. Anselmetti and E. Meyer. Dordrecht, Kluwer Academic Publishers. E:286: 15-34.
marti_47.pdf

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[212] Krausch, G., Hipp, M., Boeltau, M., Marti, O. and Mlynek, J. (1995). "High-Resolution Imaging of Polymer Surfaces with Chemical Sensitivity." Macromolecules 28(1): 260-3.
marti_28.pdf  
We have studied the potential of friction and stiffness measurements with high spatial resoln. for the surface characterization of glassy polymers. We present exptl. evidence for quasi-chem. sensitivity on a heterogeneous surface consisting of polystyrene islands on a poly(Me methacrylate) base layer. Although similar in their bulk mech. properties, the two polymers are easily distinguished by their different nanomech. behavior. As an example, we characterize the domain pattern formed after spinodal decompn. of a sym. blend of the two polymers.
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[213] Brunner, R., Gall, S., Wilke, W. and Zrinyi, M. (1995). "Formation of fractal structures by aggregation of anisometric iron(III)hydroxide particles." Physica A 214(2): 153-61.

Coagulation of anisometric iron(III)hydroxide sols has been studied by dynamic light scattering, TEM and ultra-small-angle X-ray scattering. The anisometry of rod-like individual colloidal particles can be characterised with a mean aspect ratio of 10. It was established for the first time, that the aggregates formed by coagulation of anisometric particles show definite fractal structure with a mass fractal dimension of 1.95+or-0.05. (14 References).
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[214] Hurler, W., Pietralla, M. and Hammerschmidt, A. (1995). "Determination of thermal properties of hydrogenated amorphous carbon films via mirage effect measurements." Diamond & Related Materials 4(7): 954-7.

We present a new photothermal method using the mirage effect to measure the thermal properties of thin film materials in a contactless, non-destructive way without the need for sample preparation. A complete theoretical treatment of the mirage signal generation in the case of an homogeneous N-layer system allows the thermal conductivity and the thermal diffusivity to be deduced from experimental data. We investigated the thermal properties of a wide variety of diamond-like or amorphous hydrogenated carbon films deposited in a capacitively coupled parallel plate r.f.-plasma reactor. (10 References).
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[215] Kilian, H. G. (1995). "Fluctuation dynamics and relaxation in glass-forming liquids polymer networks and low molecular weight systems." Colloid & Polymer Science 273(9): 828-41.

The dynamics in glass forming liquids is described by defining conformons as a new type of bosons. Activation or deactivation can be induced. Most significant is that conformons may spontaneously decay. This allows to redistribute all the modes so as to maximize the entropy. Stationary equilibrium then is characterized by broad conformon distribution. This universal spectrum has topologically analogous origins as the black body radiation. It is possible to describe the temperature dependence of fluctuations i.e. of their contribution to the heat capacity accounting empirically also for the glass transition. It appears to be reasonable to define relaxation mode spectra. To this end, the number complexions of a conformon and its mean relaxation time are related to each other by a power law. Its key parameter alpha describes empirically how fluctuations and relaxation modes are connected with each other. Under thermo-rheological simple conditions actual relaxation time spectra are then obtained by a congruent shift of the whole spectrum (WLF-procedure). The shape of a relaxation time spectrum does not depend on temperature or pressure (pressure-temperature-frequency relationship). Moreover, it is also strain-, strain-type and strain-rate invariant. The new approach is successful in deducing the master curve of the real and the imaginary parts of the complex shear modulus or of the complex compliance. Dielectric susceptibility data of polymers and low molecular glass formers are satisfactorily reproduced. In contrast to the dielectric experiments mechanical relaxation behave more complex. In networks junctions fluctuations take influence which is increased in filler loaded rubber of poly-vinyl-chloride. Interpretations are discussed on a set of representative experiments. The description of all these experiments proves the utility of the conformon model the physical ideas of which are discussed in this paper. (59 References).
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[216] Metzler, R., Schick, W., Kilian, H. G. and Nonnenmacher, T. F. (1995). "Relaxation in filled polymers: a fractional calculus approach." Journal of Chemical Physics 103(16): 7180-6.

In recent years the fractional calculus approach to describing dynamic processes in disordered or complex systems such as relaxation or dielectric behavior in polymers or photo bleaching recovery in biological membranes has proved to be an extraordinarily successful tool. In this paper we apply fractional relaxation to filled polymer networks and investigate the dependence of the decisive occurring parameters on the filler content. As a result, the dynamics of such complex systems may be well-described by our fractional model whereby the parameters agree with known phenomenological models. (25 References).
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[217] Weishaupt, K., Krbecek, H., Pietralla, M., Hochheimer, H. D. and Mayr, P. (1995). "Pressure dependence of the elastic constants of poly(methyl methacrylate)." Polymer 36(17): 3267-71.

We report measurements of the hydrostatic pressure dependence of the elastic constants of poly(methyl methacrylate) using high resolution Brillouin spectroscopy. We have measured the density rho (p) up to 500 MPa, and the longitudinal and transverse sound velocities up to 300 MPa. We have calculated the bulk modulus, Youngs modulus, shear modulus and Poisson's ratio. Initially there is a strong increase in the intensity of the shear phonons which levels off at p>100 MPa. At this pressure a dispersion-like step in the shear modulus as well as a decrease in the bulk modulus is found, which is tentatively discussed as a 'weak glass transition' within the glass. (16 References).
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[218] Weishaupt, K. and Pietralla, M. (1995). "The elastic behaviour of polycarbonate in the glassy state determined by Brillouin scattering." Journal of Materials Science 30(21): 5457-60.

Measurements of the temperature and hydrostatic pressure dependence of the elastic constants of amorphous polycarbonate in the glassy state using high-resolution Brillouin spectroscopy are reported. It was found that the temperature and the pressure dependence of the longitudinal and the transverse sound velocity are strictly linear, in contrast to the behaviour found in polymethyl methacrylate (PMMA). A simple equation for the behaviour of the elastic constants c/sub 11/ and c/sub 44/, and the shear, Young's and bulk modulus, can be given, which fits the experimental data well. (10 References).
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[219] Hipp, M., Mertz, J., Marti, O. and Mlynek, J. (1994). Near-field imaging and simultaneous charge detection with a semiconductor probe tip. EQEC'94.
marti_218.pdf
We present quantitative measurements of mechanical forces induced by evanescent light on a semiconductor probe tip via the surface photovoltage effect (SPV). The semiconducting tip is used as a sensitive sub-wavelength sized light detector. Scanning techniques allow the profiling of laterally inhomogeneous light distributions such as a standing wave pattem. A combination with the “local charge force microscopy” provides simultaneous information on local charge distributions on the surface.’
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[220] Hipp, M., Mertz, J., Mlynek, J. and Marti, O. (1994). Near-field microscopy with a semiconductor probe tip. IQEC '94, Anaheim, CA, USA, 8-13 May, Opt. Soc. America.
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[221] Müller, T., Jäkle, U., Krausch, G., Marti, O. and Mlynek, J. (1994). Rasterkraft- und Reibungsmikroskop für Anwendungen im Ultrahochvakuum. GermanyTo top

[222] Burger, J., Dietler, G., Binggeli, M., Christoph, R. and Marti, O. (1994). "Aspects of the surface roughness of ceramic bonding tools on a nanometer scale investigated with atomic force microscopy." Thin.Solid.Films. 253: 308-310.
marti_56.pdf  
J Burger, Ctr Suisse Electr & Microtech SA, Maladiere 71, CH-2007 Neuchatel, Switzerland Ceramic bonding capillaries were studied using a stand- alone atomic force microscope (AFM) demonstrating the importance of nanoscale characterization for industrial quality control. Bonding tools represent an example of a nanotribological system in industry as the friction at the bonding wire/capillary interface is responsible for the formation of the contact between the bonding wire and bonding pad. The detailed structure and homogeneity of micro- and nanometer scale structures on the surface are crucial for the performance of the capillary during the bonding process. The surface of bonding tools prepared under different conditions could be imaged at the very end, giving information on the formation of a nanoscale roughness. A special roughness analysis based on methods of fractal analysis was used in order to obtain a direct correlation between the roughness and lateral length scale of the AFM images
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[223] Perrot, E., Dayez, M., Humbert, A., Marti, O., Chapon, C. and Henry, C. R. (1994). "Atomic-scale resolution on the MgO(100) surface by scanning force and friction microscopy." Europhysics Letters 26: 659-663.

MgO(100) surfaces have been imaged at atomic-scale resolution by scanning force and friction microscopy (SFFM). The single crystals of MgO were cleaved and studied in dry air using a small loading force (4.10-10 N). Topographic and friction images reveal a square lattice of protrusions with a measured spacing of 0.274 nm. This value is close to the 2D surface lattice parameter of the MgO(100) surface (0.299 nm). The largest corrugation observed in the topographic images is 0.04 nm. Large-scale images reveal nearly parallel cleavage steps, separated by an average distance of 150 nm and 0.4 nm high.
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[224] Marti, O. (1994). Near field optical microscopy and spectroscopy. Digest CLEO/Europe 1994 (Amsterdam, 28 August - 2 September 1994).
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[225] Marti, O. (1994). Scanning force and friction microscopy applied to organic and biological samples. Proceedings of ICEM'13 (Paris 17-22 July 1994).
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[226] Mertz, J., Hipp, M., Mlynek, J. and Marti, O. (1994). "Optical Near Field Imaging with a Semiconductor Probe Tip." Applied Physics Letters 64: 2338-2340.
marti_45.pdf  
We present an optical near-field detection mechanism based on optical modulation of the image force between a semiconducting probe tip and a glass surface. The modulation stems from a phenomenon called surface photovoltage. The performance of the mechanism for near-field imaging is demonstrated by using a scanning force microscope over a standing evanescent light wave. The lateral resolution is found to be 170 nm (subwavelength) and a representative minimum detectable power is 0.1 pW/ square root Hz in air. We develop a simple theoretical model and discuss some possible applications.
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[227] Bielefeldt, H., Hörsch, I., Krausch, G., Lux-Steiner, M., Mlynek, J. and Marti, O. (1994). "Reflection-Scanning Near-Field Optical Microscopy and Spectroscopy of Opaque Samples." Appl.Phys.A-Solid.Surf. 59: 103-108.
marti_44.pdf  
Opaque samples are imaged by Scanning Near-field Optical Microscopy (SNOM) in reflection mode: A quartz glass fiber tip is used both to illuminate the sample and to collect light locally reflected from or emitted by the surface. The collected light is coupled out by a 2 x 2 fiber coupler and fed into a grating spectrometer for spectral analysis at each sampled point. The tip-sample distance is controlled by a shear-force feedback system. The simultaneous measurement of topography and optical signals allows an assessment of imaging artifacts, notably topography-induced intensity changes. It is demonstrated that an optical reflectance contrast not induced by topographic interference can be found on suitable samples. Local spectral analysis is shown in images of a photoluminescent layer
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[228] (1994). 28th Europhysics Conference on Macromolecular Physics. Steinkopff. K. H-G and P. M
The following topics were dealt with: glass transition in polymer molecules and networks; Monte Carlo simulation of glass transition of polymer melts; dynamics in disordered systems; glass transition of partially ordered macromolecules; relaxation in networks strained in glass transition regime; cooperative dynamics models; polymers and the phase rule; phase equilibria in polymer/solvent systems; and colloidal suspensions as model liquids and solids.
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[229] Hurler, W. and Pietralla, M. (1994). "Thermal characterization of bulk and thin film materials using the mirage-method." Journal de Physique IV 4(C7): 627-30.

The photothermal laser beam deflection (PTD) is used to measure the thermal properties of bulk solids and thin film materials. A complete theoretical treatment of the mirage-deflection in the case of a 4 layer-model (gas/film/substrate/backing) and a line heating source has been performed. The thermal properties can be obtained by fitting the theoretical expression to the experimental data. The experimental setup is described and experimental results for the thermal diffusivities of bulk solids over a range of 3 decades are presented. The errors caused by an incorrect assignment of fixed parameters in the non-linear least-square-fitting procedure are studied. A sensitivity study for a film-substrate-system is shown. (4 References).
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[230] Kilian, H. G. (1994). "Universal properties of polymer networks." Physica Scripta.

The use of thermodynamics of irreversible processes allows one to describe time dependent deformation phenomena of polymer networks. It is shown that linear relaxation modes are coupled to the network ("global level"). The constitutive van der Waals equation is characterized by a strain, strain-type and a strain-rate independent memory function. Stress-strain cycles in the glass-transition regime can be described. The dynamics of networks can be characterized by introducing the concept of conformons. Conformons are shown to be Bosons with a photon statistics. Conformons in equilibrium have a self-energy- and self-entropy-term. They can be excited or emitted. Conformons also decay spontaneously. In the stationary limit a broad conformon spectrum results which is typical for glass forming liquids (including polymers). Relaxation-and retardation-time spectra are shown to be related to the conformon spectrum. Mechanical and dielectric relaxation measurements (even of low molecular weight glass formers) are fairly well reproduced. The dynamical structure factors of the incoherent neutron scattering can also be computed. (25 References).
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[231] Kraus, V., Kilian, H. G. and Saile, M. (1994). "Relaxation mode coupling and universality in stress-strain cycles of networks including the glass transition region." Polymer 35(11): 2348-54.

The temperature and strain rate dependence of stress-strain cycles of poly(methyl methacrylate) (PMMA) networks are investigated. The van der Waals theory of polymer networks describes the quasi-static stress-strain behaviour. Time-dependent effects during deformation are treated within the framework of irreversible thermodynamics. The Gibbs function of the network is extended by an appropriate set of hidden variables. The orthogonal relaxation modes of the Onsager type, represented by these hidden variables, couple in an isotropic and scalar manner with the network (relaxation mode coupling model). The time dependence of the nominal force is characterized by a relaxation time distribution that is independent of strain and of the deformation mode. In the thermodynamic limit the strain-energy of the network is the fundamental state of reference even at large strains. In the rubbery region the Williams-Landel-Ferry (WLF) equation describes thermorheological simple behaviour. In the glass transition region, the WLF-shift procedure fails when the mean relaxation time becomes large (WLF boundary). A specific, but universal modification of the WLF-shift procedure due to the strain-induced process of polymer segments changing place is observed and results in a unique frequency-temperature relationship (elastic and rheological simple behaviour). (29 References).
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[232] Lankarani, H. M. and E., N. P. (1994). "Continuous Contact Force Models for Impact in Multibody Systems, Nonlinear Dynamics." 5: 193-207.
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[233] Mergenthaler, D. B. and Pietralla, M. (1994). "Heat conduction in highly oriented polyethylene." Zeitschrift fur Physik B Condensed Matter 94(4): 461-8.

The variety of structures found in polymers makes it impossible to thoroughly understand all the mechanisms affecting heat conduction. With the example of polyethylene it is shown that highly oriented polymers can be treated as strong anisotropic continua in the defect scattering limit. Using direction dependent sound velocities from Brillouin scattering we find elastic contributions to be dominated by the angular dependence of the phonon density. The direction dependence of the specific heat contributions is accounted for by using the Debye formalism in q-space. The cut off wave vector is determined by fitting the low temperature specific heat. The resulting relaxation lengths turn out to be largely temperature independent in agreement with the assumption of predominant structure scattering. At 8 K<17>
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[234] Schwede, J., Kohler, L., Grossmann, H. P., Pietralla, M. and Burrows, H. D. (1994). "Raman spectroscopic investigations of the structure and phase transitions of liquid crystalline lead(II) alkanoates." Liquid Crystals 16(2): 267-76.

Lead(II) alkanoates with even chain lengths from octanoate to octadecanoate have been investigated by Raman spectroscopy. In the low frequency region, transverse and longitudinal acoustical modes (TAM, LAM) have been assigned. It was shown that LAM-1 is the vibration of the double chain with the node of the vibration in the Pb/sup 2+/ layer. A fully extended conformation of the chains in the low temperature phase was confirmed. The frequencies and intensities of the LAMs as compared with those of the alkanes and the fatty acids led to an estimate of the force constant and polarizability of the Pb/sup 2+/-COO/sup -/ bond relative to the C-C bond. The defects at the chain ends were investigated in the rho (CH/sub 3/) and nu (CC) region. For the intermediate (CM) phase, both the Pb/sup 2+/ layer distance reduction and the chain length independent enthalpy contributions can be attributed mainly to defects at the chain ends. (21 References).
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[235] Tregub, A., Privalko, V. P., Kilian, H. G. and Marom, G. (1994). "The thermoelastic behaviour of semicrystalline and of glassy poly(ether-ether-ketone)." Applied Composite Materials 1(2): 167-76.

A thermoelastic evaluation, based on simultaneous measurements of the mechanical work and of the concomitant heat of deformation by a stretching micro calorimeter, was performed on semicrystalline and glassy PEEK. The objective of this study was to utilize the sensitive technique to detect differences that would account for observed effects of microstructure on mechanical performance. A clear difference was detected beyond a 0.6% strain, where the behaviour of glassy PEEK began to exhibit inelastic features such as yielding and plastic deformation. This difference between the glassy and the semicrystalline polymers was considered the reason for the superior mechanical fatigue and fracture properties produced by the latter microstructure. (17 References).
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[236] Marti, O., Colchero, J., Bielefeldt, H., Hipp, M. and Linder, A. (1993). "Scanning Probe Microscopy: Applications in Biology and Physics." Microsc.Microanal.Microstruct. 4(5): 429-440.
marti_43.pdf  
Scanning probe microscopes can probe a variety of quantities characterizing surfaces. This overview paper describes techniques applicable in an ambient environment and having the power to distinguish different materials: the scanning force and friction microscope and the scanning near-field optical microscope combined with a spectrometer. The basic operating principles of these two microscopes are described. Selected experiments point to possible future applications: we discuss scanning force and friction microscopy of ZnSe on GaAs and of Na, K- ATPase and near-field optical microscopy of a grating and of micropores
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[237] Binggeli, M., Christoph, R., Hintermann, H. E. and Marti, O. (1993). "Atomic Scale Tribometer for Friction Studies in Controlled Atmosphere." Surface and Coatings Technology 62: 523-528.
marti_42.pdf  
To obtain a more fundamental understanding of macroscopic tribological processes, investigations on a microscopic or even atomic scale have to be undertaken. Macroscopic mechanical concepts of adhesion and friction phenomena are not adequate for explaining “nanomechanics”. The development of local probe techniques (scanning tunneling microscopy, atomic force microscopy) offered powerful new tools for studying microscopic, i.e. local, surface properties. One possible application of these instruments is local friction investigation by simulating a single asperity contact of a real surface with an atomic force microscope tip, and measuring normal and lateral forces occurring at the tip while imaging a sample. Withrespect to the enormous effect ofenvironmental conditions on which local tribological interactions take place, rigorous control of the atmosphere is needed. We present details ofan instrument suited for carrying out local friction investigations in controlled atmospheric conditions or on samples embedded in an extended experimental environment. The instrument’s conception and possible applications are described, especially its combination with an electrochemical cell and potentiostatic control of a sample immersed in electrolytes. First results obtained with such a set-up are presented.
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[238] Marti, O. (1993). "Friction and measurement of friction on a nanometer scale." Surface and Coatings Technology 62: 510-516.
marti_41.pdf  
The emerging field of nanotechnology deals with mechanical structures and their properties in the nanometer range. The nanometer length scale is mostly beyond the resolution of classical tribometers. However, the scanning force and friction microscope operated as a tribometer is a suitable tool for the investigation of nanotribological properties. The scanning force and friction microscope measures simultaneously forces normal and parallel to the sample surface with a resolution down to the atomic scale. Measurements of the friction coefficient of silicon nitride tips against a flat mica surface and against a silicon oxide surface with indium clusters are discussed. It is shown that a two-dimensional histogram analysis yields quantitative data on the distribution of the indium on a nanometer scale. The chemical sensitivity of the scanning force and friction microscope operated under ambient conditions makes this instrument a promising candidate for a standardized tool in nanotribology.
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[239] Marti, O. (1993). "Nanotribology: Friction on a Nanometer Scale." Physica Scripta T49: 599-604.
marti_40.pdf  
The submicrometer length scale is mostly beyond the resolution of classical tribometers. The scanning force and friction microscope operated as a nanotribometer is a suitable tool for the investigation of nanotribological properties. The scanning force and friction microscope measures simultaneously forces normal and parallel to the sample surface with a resolution down to the atomic scale. The setup of a scanning force microscope based nanotribometer, its calibration and the methods for quantitative data analysis are discussed. It is shown that a two-dimensional histogram analysis yields quantitative data on the distribution of the indium on a nanometer scale. The concepts are applied to the analysis of a silicon oxide surface with indium clusters are discussed. The chemical sensitivity of the scanning force and friction microscope operated under ambient condition makes this instrument a promising candidate for a standardized tool in nanotribology.
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[240] Bielefeldt, H., Hecht, B., Herminghaus, S., Marti, O. and Mlynek, J. (1993). Direct Measurement by Scanning Tunneling Optical Microscopy of the Field Enhancement caused by Surface Plasmons. Near Field Optics. D. Courjon and D. Pohl. Dordrecht, Kluwer. 242: 281-286.
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[241] Marti, O. and Balykin, V. (1993). Light Forces. Near Field Optics. D. Courjon and D. Pohl. Dordrecht, Kluwer. 242: 121-130.
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[242] Linder, A., Apell, H.-J., Colchero, J. and Marti, O. (1993). Na,K-ATPase: Preparation and Scanning Force Microscopy. STM and SFM in Biology. O. Marti and M. Amrein. San Diego, Academic Press: 275-308.
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[243] Marti, O. (1993). Scanning Probe Microscopy: an Introduction. STM and SFM in Biology. O. Marti and M. Amrein. San Diego, Academic Press: 1-143.
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[244] Marti, O. and Amrein, M., Eds. (1993). STM and SFM in Biology. San Diego, Academic Press.

[245] Binggeli, M., Christoph, R., Hintermann, H.-E., Colchero, J. and Marti, O. (1993). "Friction Force Measurements on Potential Controlled Graphite in Electrolytic Environment." Nanotechnology 4: 59-63.
marti_34.pdf  
The authors show the simultaneous recording of normal and lateral forces arising in scanning force and friction microscopy on a potential controlled sample immersed in aqueous electrolyte. As a liquid film is present on virtually all solid surfaces under ambient conditions, it is important to control the properties of the solid/liquid interface. In order to obtain reliable information on the friction behaviour of such a surface, a set-up for potentiostatic control of the sample was established. Experiments have been carried out with a stand-alone scanning force and friction microscope (SFFM), combined with an electrochemical cell providing potential control of the sample. First results of simultaneous normal and friction force measurements, obtained on highly oriented pyrolytic graphite (HOPG) immersed in NaClO4, demonstrate the promising potential of the method.
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[246] Marti, O., Colchero, J. and Mlynek, J. (1993). Friction and Forces on an Atomic Scale. Nanosources and Manipulations of Atoms under High Fields and Temperatures: Applications. V. T. Binh, N. Garcìa and K. Dransfeld. Dordrecht, The Netherlands, Kluwer Academic Publishers. E 235: 253-269.
marti_33.pdf
The Scanning Force and Friction Microscope based on the optical lever deflection method measures simultaneously forces normal and parallel to the sample surface with a resolution of down to the atomic scale. Lateral forces on a sub-nanometer scale consist of conservative and dissipative terms. A simple model for the origin of friction on an atomic scale is discussed. Using micro fabricated cantilevers the friction coefficient of silicon nitride tips against a flat mica surface was determined at a range of loads. On a larger scale the material dependency of friction is discussed and it is shown that this property leads to a chemical sensitivity of the Scanning Force and Friction Microscope. The sensitivity to lateral forces can be used to determine adhesion properties of small structures. The Scanning Force and Friction Microscope may be useful for studies of friction and wear inaccessible to classical equipment.
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[247] Mertz, J., Marti, O. and Mlynek, J. (1993). "Regulation of a Microcantilever Response by Active Control." Applied Physics Letters 62: 2344-2346.
marti_32.pdf  
A feedback mechanism is used to control the forces incident on a mechanical microcantilever as a function of the monitored cantilever motion. The control is effected by modifying the intensity of an auxiliary laser beam that generates a thermally induced stress. The feedback is designed to reduce the effective resonance quality factor of the cantilever. The resultant regulation of the cantilever motion is shown to improve the measurement dynamics in atomic force microscopy, without significantly degrading the signal to noise ratio.
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[248] Marti, O., Bielefeldt, H., Herminghaus, S., Leiderer, P. and Mlynek, J. (1993). "Near Field Optical Measurement of the Surface Plasmon Field." Optics Communications 96: 225-228.
marti_31.pdf  
The intensity of the evanescent electromagnetic wave of optically excited surface plasmons was measured directly using a scanning tunneling optical microscope (STOM) setup. When resonant coupling of the driving field to the surface plasmons was achieved, the measured intensity was increased by a factor of 30 larger than the corresponding evanescent wave intensity on a bare glass surface, in agreement with the theoretical prediction. Experimental results are presented for three laser wavelengths (514 nm, 633 nm, 670 nm). Possible applications of the technique to study surface plasmon field are discussed.
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[249] Haas, W., Zrinyi, M., Kilian, H. G. and Heise, B. (1993). "Structural analysis of anisometric colloidal iron(III)-hydroxide particles and particle-aggregates incorporated in poly(vinyl-acetate) networks." Colloid & Polymer Science 271(11): 1024-34.

Anisometric colloidal iron(III)hydroxide particles and particle aggregates were incorporated in elastic poly(vinyl acetate) networks. A novel method has been developed to fix the colloidal structure of deformed samples. Digitalized image analysis has been applied in order to evaluate the micrographs. The rod-like particles allow for studying the local deformation and orientation due to uniaxial and triaxial deformations. The density correlation function as well as the micrographs show that the structure of aggregates is not influenced by the strain. Due to strong attractive interactions between the colloidal particles the developing strain is not enough to destroy the aggregate structure. The orientation behavior of the model filled networks can be satisfactorily described by using the affinity principle. (22 References).
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[250] Kraus, R., Payer, A. and Wilke, W. (1993). "Acoustic emission analysis and small-angle X-ray scattering from microcracks during deformation of ETFE composites." Journal of Materials Science 28(15): 4047-52.

During the deformation of an unfilled matrix of ethylene-tetrafluoroethylene (ETFE), microcracking was observed by small-angle X-ray scattering (SAXS), although it does not cause significant acoustic emission because the released energy is too small to be detected (size of' microcrack<<11>
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[251] Krbecek, H., Kruger, K. and Pietralla, M. (1993). "Poisson ratios and upper bounds of intrinsic birefringence from Brillouin scattering of oriented polymers." Journal of Polymer Science Part B Polymer Physics 31(11): 1477-85.

To overcome the difficulties in measuring high-frequency shear constants of polymeric materials by ultrasonic or Brillouin scattering techniques, the authors extrapolate results from oriented materials to zero birefringence. Shear constants C/sub 44/ in the high-frequency limit (GHz) are determined for polyethylene, poly(ethylene terephthalate), poly(vinyl chloride), poly(methyl methacrylate), and polycarbonate using Brillouin scattering. Accurate values of Poisson's ratio are derived. The extrapolation to full orientation using an amended Moseley relation gives upper bounds for the 'intrinsic birefringence'. Changes in the character of the orientation process are easily detected by monitoring the mode numbers, which are defined by analogy of Poisson's ratio. Extrapolation of these ratios to their upper bound 0.5 gives an independent check of the maximum intrinsic birefringence. (37 References).
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[252] Rehm, B., Huang, B., Heise, B., Kilian, H. G. and Heitz, W. (1993). "Structure and thermodynamics of liquid crystalline polyesters and copolyesters." Colloid & Polymer Science 271(6): 529-38.

The authors investigated the influence of aliphatic spacers with different lengths on the phase diagram of LC main chain copolyesters, based on X-ray and calorimetric measurements. The thermodynamic description is based on the assumption that considers each sequence, composed of mesogenic unit and spacer, as a 'particle'. This allows one to interpret the phase diagram of copolyesters as a quasi binary system. General features, such as an azeotropic point found in LC copolyesters, are related to the differences of the excess energies in LC and other phases. (22 References).
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[253] Wei-Guo, P., Strauss, M., Pieper, T. and Kilian, H. G. (1993). "X-ray diffraction and model calculation on carbon blacks." Molecular Physics 80(2): 419-29.

Wide angle X-ray scattering (WAXS) experiments were performed on degraphitized carbon blacks to investigate their structure which is believed to be distorted and to be responsible for the strong adhesion on the particle surface. For comparison the measurement of a graphitized sample was also carried out. A structural model has been developed to describe the turbostratic and lubricostratic carbon blacks. The orientational and translational disorders of carbon layers are formulated by averaging the structural amplitudes of layers. The Percus-Yevick approximation for hard-core systems in one dimension is applied to characterize the positional fluctuation of layer stacking along the layer normal. The finite layer stack size is accounted for by a simple shape factor. The diffraction patterns calculated from the model agree very well with the measurements of both graphitized and degraphitized carbon blacks. It is found that the degraphitized carbon blacks contain probably also the lubricostratic disorder. Five structural parameters, namely packing density, layer diameter, stacking height, interplanar distance and projected carbon-carbon bond length, can be accurately determined by a careful fit of the experimental curves to the model calculation. The quantitative X-ray analysis by model calculation leads to a more detailed and accurate characterization of the carbon black structure. (18 References).
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[254] Marti, O. and Colchero, J. (1992). "Reibungsmikroskopie." Physikalischen Blätter 12: 1007-1009.
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[255] Hipp, M., Bielefeldt, H., Colchero, J., Marti, O. and Mlynek, J. (1992). "A Stand-Alone Scanning Force and Friction Microscope." Ultramicroscopy 42-44: 1498-1503.
marti_29.pdf  
The authors present a new design for a compact stand-alone force and friction microscope. Both the force sensor and the scanning unit are mounted on the microscope head, thus allowing the investigation of virtually all surfaces, independent of thickness and size, and minimizing the geometrical dimension. The beam deflection method in a collinear arrangement is used to detect the normal force and the friction force. The cantilever is fixed to the scanning piezo. The influences of the scanning motion on the force signal and the compensation schemes are discussed. The new design of the SFM allows a combination of optical surface manipulation and real-time detection of the stimulated processes with the scanning force microscope. The set-up also makes it possible to work under fluids.
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[256] Apell, H.-J., Colchero, J., Linder, A., Marti, O. and Mlynek, J. (1992). "Na,K-ATPase in crystalline form investigated by Scanning Force Microscopy." Ultramicroscopy 42-44: 1133-1140.
marti_28.pdf  
Na,K-ATPase has been isolated in purified membrane fragments from kidney tissue and crystallized by phospholipase treatment to obtain two-dimensional, membrane-bound protein crystals. Scanning force microscopy has been used to identify and analyze the topography of the membrane fragments. Specific patterns in accordance with electron microscopic images have been found. In biological under physiological conditions the scanning force is a crucial parameter for the resulting image at high resolution.
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[257] Marti, O., Ruf, A., Hipp, M., Bielefeldt, H., Colchero, J. and Mlynek, J. (1992). "Mechanical and thermal effects on force microscope cantilevers." Ultramicroscopy 42-44: 345.
marti_27.pdf  
In an optical lever set-up one or two modulated laser beams of 0.1 to 6 mW modulation amplitude at a wavelength of 670 nm were focused at uncoated and gold-coated microfabricated cantilevers. The motion of the levers was analyzed by an optical lever set-up. The mechanical resonance (30 to 60 kHz) of the cantilevers was excited by the modulated light both in air and under vacuum conditions (10-6 mbar). The measured resonance frequencies and the width of the resonances were identical to the values found by exciting the cantilevers by piezo ceramics. At low frequencies under vacuum conditions, the authors found an increase of the oscillation amplitude with decreasing frequency. The time constant of this increase is of the order of 5 ms. At the resonance frequency of uncoated cantilevers light pressure effects dominate thermal effects; the resonance is thus excited by light pressure. Gold-coated cantilevers, however, are driven by the bimetal effect, even above 10 kHz. A possible application of the light pressure effects is the use of a modulated light beam in the attractive mode operation of a scanning force microscope to excite the cantilever oscillation.
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[258] Linder, A., Colchero, J., Apell, H.-J., Marti, O. and J. Mlynek (1992). "Scanning Force Microscopy of Diatom Shells." Ultramicroscopy 42-44: 329-332.
marti_26.pdf  
The authors have imaged surfaces of several diatom species by scanning force microscopy with image areas of some squared micrometers. The algae cells were collected from a mud sample out of a small pond, rinsed briefly with ethanol to clean and immobilize them and deposited on a glass slide. The ease of obtaining images with a resolution of several ten nanometers makes the scanning force microscope competitive with scanning electron microscopy at medium magnification.
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[259] Colchero, J., Marti, O., Bielefeldt, H. and Mlynek, J. (1992). "Scanning Force and Friction Microscopy." Phys. stat. sol. (a) 131: 73-75.
marti_25.pdf  
Using the optical lever technique the authors have developed a scanning force microscope (SFM) which simultaneously measures the topography as well as the lateral force on the tip in the scanning direction. This new microscope, the scanning force and friction microscope (SFFM), is sensitive to the chemical composition of the surface and should open new frontiers in tribology.
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[260] Koenen, J. A. (1992). "Observation of the heat exchange during deformation using an infra-red camera." Polymer 33(22): 4732-6.

The necking process during deformation of polycarbonate was observed with an infra-red (i.r.) camera. After calibration of the i.r. camera and determination of the emissivity of the sample, it is possible to transform the thermal image into a temperature image. Calculations, based on the heat conduction equation including heat sources and heat loss, yield a quantitative description of the measured temperature pattern and therefore the heat produced by the necking process. The method was checked by comparison with experiments done with a stretching calorimeter. The total balance of energy, heat and work could be measured as a function of the stretching rate. A transition from an increase of internal energy at low strain rates to an unchanged internal energy-all work is converted into heat-at high neck velocities is observed. (16 References).
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[261] Weis, E. M. and Wilke, W. (1992). "Structure and mechanical behaviour of short glass fibre-reinforced ethylene-tetrafluoroethylene copolymers. I. Influence of the filler on mechanical behaviour and structure." Journal of Materials Science 27(7): 1876-82.

A copolymer of ethylene tetrafluoroethylene hexafluoropropylene and perfluoropropylvinyl-ether has been investigated. Uniaxial tensile tests at small strains showed improved mechanical properties, when the copolymer was filled with short glass fibres. This is due to a change in superstructure, as can be seen with small-angle X-ray scattering (dynamic measurements during heating with synchrotron radiation). This results in some kind of bonding between matrix and fibres: scanning electron micrographs of fracture surfaces obtained at temperatures between -192 and +160 degrees C show the bonding as well as the nucleating influence of the fibres on the matrix in their surroundings. Wide-angle X-ray scattering up to 170 degrees C (made with a Guinier camera) shows that the crystalline structure itself was not influenced by the fibres and that the crystallites in the copolymer were longitudinally disordered to a high degree. (13 References).
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[262] Weis, E. M. and Wilke, W. (1992). "Structure and mechanical behaviour of short glass fibre-reinforced ethylene-tetrafluoroethylene copolymers. II. Description of the mechanical behaviour using rheological models." Journal of Materials Science 27(7): 1883-91.

For pt.I see ibid, vol.27, no.7, p.1876-82 (1992). The mechanical behaviour of a copolymer, consisting of ethylene, tetrafluoroethylene, hexafluoropropylene and perfluoropropylvinylether, unfilled and filled with short glass fibres has been investigated for strains less than 5%. Different deformation modes at room temperature and at 80 degrees C were recorded with a video system. The resulting stress-strain, relaxation and shrinkage curves are described with a model consisting of seven basic rheological elements of three different types: spring (Hooke model), dashpot (Newton model) and slip-element (St. Venant model). This seven-element model gives a very good approximation of all the investigated deformation modes and allows an interpretation of relaxation and retardation times of polymer segments. The plastic deformation, described by the slip-element, is assumed to be caused by slip processes in the highly disordered crystallites of the copolymer matrix. (10 References).
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[263] Marti, O. (1991). Kraftmikroskopie: Grundlagen und Anwendungen in Biologie und Physik. Universität Konstanz, Habilitationsschrift (kumulativ)marti_220.pdf
Kraftmikroskopie und Rastertunnelmikroskopie wurden mit grossem Erfolg auf eine Vielzahl von wissenschaftlichen Fragen angewandt. Die Rastertunnelmikroskopie ermöglichte, unter anderem, ein wesentlich vertieftes Verständnis der Physik der Halbleiteroberflächen. Mit der Kraftmikroskopie können leitende und nichtleitende Oberflächen, organische Proben, aber auch magnetische Phänomene untersucht wer-den, letzteres mit einer Eleganz die vorher nicht möglich war.
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[264] Colchero, J., Marti, O., Mlynek, J., Humbert, A., Henry, C. R. and Chapon, C. (1991). "Palladium Clusters on Mica: A Study by Atomic Force Microscopy." Journal of Vacuum Science and Technology B9: 794-797.
marti_24.pdf  
A compact scanning force microscope with a force sensor based on the light beam deflection method was used to study palladium clusters on mica. The force microscope was equipped to measure topography of the sample surface and the friction force between the sample and the tip. The evaporation of palladium on mica was done under UHV conditions, which were closely monitored to control both the morphology and the size of the clusters. The resulting clusters were characterized by transmission electron microscopy. The samples were then transferred in air and imaged with the scanning force microscope under ambient conditions. The diameter to height ratio near 10 and the truncated triagonal shapes of the palladium clusters agree well with the results obtained by transmission electron microscopy and with the results of a scanning tunneling microscopy study of palladium clusters on graphite. Friction images show, that the interaction between the tip and the clusters does charge them.
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[265] Kilian, H. G., Schrodi, W., Ania, F., Bayer, R. K. and Balta Calleja, F. J. (1991). "Van der Waals networks in the compressive deformation of polyethylene." Colloid & Polymer Science 269(9): 859-66.

The compressive stress-strain behavior of biaxially oriented polyethylene (PE), obtained by pressing uniaxially oriented samples, is described with the aid of the van der Waals equation of state. Results are discussed in terms of the two parameters: the biaxiality (B) and the biaxial draw ratio (( lambda )), which offer a measure of the strain along the two principal directions and of the average draw ratio on the film plane, respectively. Comparison of experimental and calculated data indicates that after compression up to very large deformations the maximum average strain ( lambda /sub m/), which is proportional to the square root of the chain length of the network, remains constant. This result supports the view that the network of entanglements is not destroyed after compression. Experiments carried out on isotropic melt crystallized PE show the presence of a network having a not very different chain length. The segment length of this network is close to the X-ray long period of the initial structure. This implies the existence of a high density of entanglements ( approximately two entanglements every three adjacent lamellae), which are rejected into the defective layer of the crystals. (29 References).
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[266] Wilke, W. and Bratrich, M. (1991). "Investigation of the superstructure of polymers during deformation by synchrotron radiation." Journal of Applied Crystallography 24(5): 645-50.

Firstly a short review of some frequently used models for fibre structures is given. Then a model, based on a three-dimensional monoclinic paracrystalline macrolattice is described. This model allows the calculation of the two-dimensional intensity distribution for the small-angle scattering from semicrystalline polymers with different orientational states. The parameters of the model result from comparison with the measured intensity. The method of analysis is applied to low-density polyethylene deformed uniaxially at different temperatures. The use of synchrotron radiation makes it possible to follow the destruction and rebuilding of the superstructure. A reversible change of the superstructure during stretching and relaxing was found for different draw ratios for very high-molecular-weight polyethylene samples. (32 References).
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[267] Marti, O., Colchero, J. and Mlynek, J. (1990). "Combined Scanning Force and Friction Microscopy of Mica." Nanotechnology 1: 141-144.
marti_23.pdf  
A scanning force microscope using the optical lever detection method was modified to measure simultaneously the force normal to the sample surface and the friction force arising from scanning. The bending of sheet-like cantilevers is used to detect the normal force whereas the twisting of the same cantilever measures the friction force. The two effects cause, to first order, orthogonal deflections of the light beam and can therefore be measured simultaneously and independently. The relationship between normal and frictional forces and the resulting deflection angles is discussed. The authors present constant-force topographs and friction images of the surface unit-cell structure of mica and of single-layer steps on mica.
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[268] Colchero, J., Marti, O. and Mlynek, J. (1990). "Ein kompaktes Kraftmikroskop aufgebaut mit Laserdiode und positionsempfindlicher Photodiode mit atomarer Auflösung." Helvetica Physica Acta 63: 491-492.
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[269] Hansma, P. K., Sonnenfeld, R., Schneir, J., Marti, O., Gould, S. A. C., Prater, C. B., Weisenhorn, A. L., Drake, B., Hansma, H., Slough, G., McNairy, W. W. and Coleman, R. V. (1990). Scanning Probe Microscopy of Liquid- Solid Interfaces. Scanning Tunneling Microscopy and Related Methods. R. J. Behm, N. Garcìa and H. Rohrer. E 184: 299-313.
marti_21.pdf
Four scanning probe microscopes, the scanning tunneling microscope (STM), the atomic force microscope (AFM), the scanning electrochemical microscope (SEM) and the scanning ion-conductance microscope (SICM) have all been used to image liquid-solid interfaces. Images in this report illustrate the variety of systems that can be studied: from iron corroding in salt water to selenium atoms in liquid nitrogen and from graphite covered with vacuum grease to proteins covered with oil. The technological and biological importance of liquid-solid interfaces has driven and will ensure rapid growth in this field.
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[270] Balta-Calleja, F. J., Santa Cruz, C., Bayer, R. K. and Kilian, H. G. (1990). "Microhardness and surface free energy in linear polyethylene: the role of entanglements." Colloid & Polymer Science 268(5): 440-6.

The microhardness of a series of melt crystallized samples of linear polyethylene was investigated in a wide range of molecular weights. The X-ray long period was analyzed to study the variation of the hardness-derived constant b as a function of molecular weight (M/sub eta /). It is pointed out that b offers a measure of the hardness depression due to the finite thickness of the lamellar crystals. The data obtained show that the increase and final leveling-off (for M/sub eta / 200000) of b with M/sub eta / parallels the concurrent increase of the surface free energy, as derived from DSC experiments. Results are discussed using the concept of chain folded lamellae as thermodynamically stable nonhomogeneous microphases. Comparison of experimental and calculated data supports the view that the number of molecular entanglements, segregated onto the defective surface boundary of the heterogeneous crystals influence the shearing mechanism within the 'mesocrystals' and thereby control the yield behavior of the material. (15 References).
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[271] Holl, B., Kilian, H. G. and Schenk, H. (1990). "Crystallization in unstretched and in stretched rubber and its thermodynamic description." Colloid & Polymer Science 268(3): 205-21.

Thermodynamics of heat- and strain-induced crystallization of networks is presented which allows the description of both crystallization modes. The network is treated as a eutectoid copolymer. Chains of different length are components representing crystallizable 'c-sequences'. For thermodynamic reasons, extended c-sequence crystals are formed in any case. It is the essential step to combine the van der Waals theory of networks and the theory of eutectoid copolymers. The solubility in the solid seems to be increased in presence of a mechanical field. The typical hysteresis in stress-strain cycles is then understandable only if 'quasi-static constraints' are introduced. These constraints are responsible for the observation that strain-induced crystallization is enforced under large overdrawings. Melting during retraction seems to run under invariant constraints. With the aid of this approach, it is possible to describe the work and the heat exchanged during stress-strain cycles of natural rubber measured in a stretching micro-calorimeter. The origins of the constraints are discussed. (68 References).
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[272] Vogt, V. D., Dettenmaier, M., Spiess, H. W. and Pietralla, M. (1990). "Orientation of the diphenylene propane unit in stretched polycarbonate from two-dimensional magic-angle-spinning NMR." Colloid & Polymer Science 268(1): 22-7.

Two-dimensional magic-angle-spinning (2D-MAS) NMR has been used to measure the orientation parameter, P/sub 2/, of the diphenylene propane unit in bisphenol-A polycarbonate oriented by the stretching to various extension ratios, lambda , at T=295 K and T=403 K. P/sub 2/ is proportional to the birefringence Delta n, with a maximum birefringence Delta n/sub 0/=0.189. There is some evidence that the order parameter P/sub 2/" of the DPP units with respect to the chain axis deviates from unity. Delta n/sub 0/ is therefore expected to be different from the birefringence, Delta n/sub 0/', of perfectly aligned chains of polycarbonate. The experimental results obtained for P/sub 2/( lambda ) are compared to those predicted by the aggregate model. (21 References).
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[273] Capua, M. S. d. and Marti, O. (1989). "Nato Advanced Study Institute on Scanning Tunneling Microscopy (STM) - Physical Concepts, Related Techniques, and Major Applications." ESNIB 89(09): 49-62.
marti_20.pdf
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[274] Hansma, P. K., Drake, B., Marti, O., Gould, S. A. C. and Prater, C. B. (1989). "The Scanning Ion-Conductance Microscope." Science 243: 641-643.
marti_19.pdf  
A scanning ion-conductance microscope (SICM) has been developed that can image the topography of nonconducting surfaces that are covered with electrolytes. The probe of the SICM is an electrolyte-filled micropipette. The flow of ions through the opening of the pipette is blocked at short distances between the probe and the surface, thus limiting the iron conductance. A feedback mechanism can be used to maintain a given conductance and in turn determine the distance to the surface. The SICM can also sample and image the local ion currents above the surfaces. To illustrate its potential for imagining ion currents through channels in membranes, a topographic image of a membrane filter with 0.80-micrometer pores and an image of the ion currents flowing through such pores are presented.
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[275] Alexander, S., Hellemans, L., Marti, O., Schneir, J., Elings, V., Hansma, P. K., Longmire, M. and Gurley, J. (1989). "An atomic-resolution atomic-force microscope implemented using an optical lever." Journal of Applied Physics 65: 164.
marti_18.pdf  
The authors present the first atomic-resolution image of a surface obtained with an optical implementation of the atomic-force microscope (AFM). The native oxide on silicon was imaged with atomic resolution, and approximately=5-nm resolution images of aluminium, mechanically ground iron, and corroded stainless steel were obtained. The relative merits of an optical implementation of the AFM as opposed to a tunneling implementation are discussed.
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[276] Marti, O., Elings, V., Haugan, M., Bracker, C. E., Schneir, J., Drake, B., Gould, S. A. C., Gurley, J., Hellemans, L., Shaw, K., Weisenhorn, A. L., Zasadzinski, J. and Hansma, P. K. (1989). "Scanning probe microscopy of biological samples and other surfaces." Journal of Microscopy 152: 803-809.
marti_17.pdf  
Scanning probe microscopes derived from the scanning tunnelling microscope (STM) offer new ways to examine surfaces of biological samples and technologically important materials. The surfaces of conductive and semiconductive samples can readily be imaged with the STM. Unfortunately, most surfaces are not conductive. Three alternative approaches were used in our laboratory to image such surfaces. 1. Crystals of an amino acid were imaged with the atomic force microscope (AFM) to molecular resolution with a force of order 10(-8) N. However, it appears that for most biological systems to be imaged, the atomic force microscope should be able to operate at forces at least one and perhaps several orders of magnitude smaller. The substitution of optical detection of the cantilever bending for the measurement by electron tunnelling improved the reliability of the instrument considerably. 2. Conductive replicas of non-conductive surfaces enabled the imaging of biological surfaces with an STM with a lateral resolution comparable to that of the transmission electron microscope. Unlike the transmission electron microscope, the STM also measures the heights of the features. 3. The scanning ion conductance microscope scans a micropipette with an opening diameter of 0.04-0.1 micron at constant ionic conductance over a surface covered with a conducting solution (e.g., the surface of plant leaves in saline solution).
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[277] Koenen, J. (1989). "Determination of the compensation band due to birefringence with dispersion and large phase differences." Journal of Materials Science 24(5): 1604-6.

The simple measurement of birefringence by means of a tilting compensator becomes difficult and unreliable when large phase differences must be compensated in samples in which dispersion of birefringence differs from that of the compensator. The problem is treated experimentally and theoretically. The result is a simple correction formula with only one parameter. A method to obtain this parameter is presented. Measurements on polycarbonate, polyethylene and polyurethane support the assumptions of the theoretical calculations. (9 References).
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[278] Koenen, J. A., Heise, B. and Kilian, H. G. (1989). "A phenomenological description of large deformations in polymeric glasses (polycarbonate)." Journal of Polymer Science Part B Polymer Physics 27(6): 1235-60.

A new description of the quasistatic deformation of polymeric glasses is presented. The stress-strain energy of a glass is defined to comprise two components: a 'solid term', which controls the low-strain range of deformation, and a 'conformational term' proportional to the first strain invariant. By introducing internal variables in terms of classical irreversible thermodynamics the stress-strain behavior and the thermoelastic properties of polycarbonate are fairly well described over the whole range of accessible strains. The necking phenomenon is interpreted as a 'constrained strain-induced phase transition' ('one-way phase transition'). A new version of a Clapeyron-Clausius equation is derived. Its application yields a new understanding of the temperature dependence of yielding of cold-drawn polycarbonate. The typical phenomena of a first-order transition, discussed in the special form of a 'one-way phase transition', have been fully identified experimentally (by microscopy, stretching-microcalorimetry, simple extension, and birefringence). Sharp phase boundaries appear just when the new phase is nucleated. (45 References).
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[279] Pietralla, M., Weeger, R. M. and Mergenthaler, D. B. (1989). "The role of phonon focussing and structure scattering in oriented semicrystalline polymers." Zeitschrift fur Physik B Condensed Matter 77(2): 219-28.

Measurements of anisotropic thermal diffusivity and of the velocity of hypersound have been performed at room temperature on one set of stretched low density polyethylene (crystallinity upsilon /sub c/=0.4). The elastic anisotropy increases with the stretching ratio lambda as does the heat conduction anisotropy. It is argued that the heat conduction cannot be traced back to properties of extended crystalline and amorphous phases. The reason for the latter is the smallness of the microphases giving rise only to non-propagating modes. Phonon focussing of superstructure phonons together with the wavelength dependence of their scattering can explain the observed effects. From the parameters found and from a semiquantitative description of the temperature dependence down to 4 K it is concluded that the main transport could be due to hopping mechanisms where the localized phonons may be fractons. It is conjectured that the energy flow is assisted or triggered by the long wave length phonons via anharmonic coupling giving rise to the dependence on direction. (47 References).
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[280] Hansma, P. K., Elings, V., Marti, O. and Bracker, C. E. (1988). "Scanning tunneling microscopy and atomic force microscopy: application to biology and technology." Science 242: 209-216.
marti_16.pdf  
The scanning tunneling microscope (STM) and the atomic force microscope (AFM) are scanning probe microscopes capable of resolving surface detail down to the atomic level. The potential of these microscopes for revealing subtle details of structure is illustrated by atomic resolution images including graphite, an organic conductor, an insulating layered compound, and individual adsorbed oxygen atoms on a semiconductor. Application of the STM for imaging biological materials directly has been hampered by the poor electron conductivity of most biological samples. The use of thin conductive metal coatings and replicas has made it possible to image some biological samples, as indicated by recently obtained images of a recA-DNA complex, phospholipid bilayer, and an enzyme crystal. The potential of the AFM, which does not require a conductive sample, is shown with molecular resolution images of a nonconducting organic monolayer and an amino acid crystal that reveals individual methyl groups on the ends of the amino acids. Applications of these new microscopes to technology are demonstrated with images of an optical disk stamper, a diffraction grating a thin-film magnetic recording head, and a diamond cutting tool. The STM has even been used to improve the quality of diffraction gratings and magnetic recording heads.
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[281] Marti, O., Gould, S. and Hansma, P. K. (1988). "Control electronics for atomic force microscopy." Review of Scientic Instruments 59(6): 836-839.
marti_15.pdf  
The control electronics for the atomic force microscope (AFM) are described. The set of electronic devices described allow convenient operation of an atomic force microscope. The key device is the force controller, which automates the otherwise tedious and time-consuming readjustment of the force to a preset value by controlling two gated feedback loops. The preset value of the force can be easily changed by simply turning a potentiometer. This automated system allows one to obtain reliable data, with known forces, despite piezoelectric creep and thermal drift in the force determining mechanical setup. The electronic devices and concepts presented work for AFMs that use tunneling, capacitance measurements, or optical interference to sense small deflections of the spring.
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[282] Marti, O., Drake, B., Gould, S. and Hansma, P. K. (1988). "Probing Surfaces with the Atomic Force Microscope." SPIE Proceedings 897: 22-25.
marti_14.pdf  
The atomic force microscope can resolve features on conducting or nonconducting surfaces down to the atomic level. The heights of features are recorded as a sharp tip scans over the surface in parallel scans. The interaction between the tip and the surface is the interaction potential between atoms. Individual carbon atoms separated by 0.146 nm have been resolved on graphite. Ordered structure on the 'native' oxide of silicon has been observed. Rows of molecules that are separated by 0.5 nm have been resolved in an organic monolayer. The key to the operation of an AFM is the development of a system for sensing tracking forces that are small enough to avoid damaging the surface. The images in this report were obtained by sensing with electron tunneling the deflection ( approximately=1-10 nm) of springs (k approximately=0.1-100 N/m) fabricated from silicon oxide or fine wires.
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[283] Marti, O., Drake, B., Gould, S. and Hansma, P. K. (1988). "Atomic force microscopy and scanning tunneling microscopy with a combination atomic force microscope/scanning tunneling microscope." Journal of Vacuum Science & Technology A 6: 2089-2092.
marti_13.pdf  
Since almost all the electronic and mechanical requirements for an atomic force microscope (AFM) are the same as for a scanning tunneling microscope (STM), it is convenient and practical to build a combination AFM/STM with interchangeable heads. The conversion from one to another can be made in a few minutes. Representative images demonstrate that atomic resolution can be obtained in both modes of operations. With the two modes of operation, it can image conductors, semiconductors and insulators.
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[284] Marti, O., Drake, B., Gould, S. and Hansma, P. K. (1988). "Atomic resolution atomic force microscopy of graphite and the 'native oxide' on silicon." Journal of Vacuum Science & Technology A 6: 287-290.
marti_12.pdf  
An atomic force microscope (AFM) can image surfaces of conductors, insulators, and even organic materials. Images of highly oriented pyrolytic graphite show atomic structure with a corrugation height of 0.03 nm. Images of the 'native oxide' layer grown in ambient pressure on a (111) facet on a (100) silicon wafer show steps. Images of the native oxide layer on a (111) silicon wafer show features 0.6 nm apart and aligned with the silicon substrate. The images shown here were obtained with an instrument that can also operate as a scanning tunneling microscope (STM); it is an AFM/STM.
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[285] Schneir, J., Marti, O., Remmers, G., Gläser, D., Sonnenfeld, R., Drake, B., Hansma, P. K. and Elings, V. (1988). "Scanning tunneling microscopy and atomic force microscopy of the liquid-solid interface." Journal of Vacuum Science & Technology A 6: 283-286.
marti_11.pdf  
The liquid-solid interface is important not only for science, but also for technology. Scanning tunnel microscopes (STMs) and atomic force microscopes (AFMs) can image and even manipulate solids covered with liquids. An image of a line 75 nm long and 5 nm wide drawn with at STM on a liquid-covered Au (111) surface demonstrates the potential for manipulating surfaces. Images of a Pt film demonstrate the ability of STMs to find new features by zooming from large-area scans down to the atomic scale. Finally, an AFM image of a liquid-covered graphite surface demonstrates atomic resolution.
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[286] Gould, S., Marti, O., Drake, B., Hellemans, L., Bracker, C. E., Hansma, P. K., Keder, N. L., Eddy, M. M. and Stucky, G. D. (1988). "Molecular resolution images of amino acid crystals with the atomic force microscope." Nature 332: 332-334.
marti_10.pdf  
The atomic force microscope has been used to image arrays of molecules at the surface of DL-leucine crystals. Lattice spacings are consistent with X-ray diffraction data. In contrast to metals and semiconductors, the surface of these amino acid crystals seems to be a simple termination of the bulk; there is no evidence of a surface reconstruction for this molecular crystal. This initial success in imaging amino acid molecules points to the potential usefulness of atomic force microscopy for imaging molecules of biological importance.
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[287] Schneir, J., Sonnenfeld, R., Marti, O., Hansma, P. K., Demuth, J. E. and Hamers, R. J. (1988). "Tunneling microscopy, lithography, and surface diffusion on an easily prepared, atomically flat gold surface." Journal of Applied Physics 63: 717-721.
marti_9.pdf  
The authors show that a gold surface with atomically flat terraces as large as (150 nm)2 can be easily prepared in air by melting a gold wire with an oxyacetylene torch. Features with characteristic dimensions as low as 10 nm can be written and observed on these terraces with a scanning tunneling microscope. The features are appreciably distorted by diffusion within an hour.
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[288] Marti, O., Ribi, H. O., Drake, B., Albrecht, T. R., Quate, C. F. and Hansma, P. K. (1988). "Atomic Force Microscopy of an Organic Monolayer." Science 239: 50-52.
marti_8.pdf  
Atomic force microscope images of polymerized monolayers of n-(2-aminoethyl)-10,12-tricosadiynamide revealed parallel rows of molecules with a side-by-side spacing of approximately=0.5 nanometer. Forces used for imaging (10-8 newton) had no observable effect on the polymer strands. These results demonstrate that atomic force microscope images can be obtained for an organic system.
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[289] Balta-Calleja, F. J. and Kilian, H. G. (1988). "New aspects of yielding in semicrystalline polymers related to microstructure: branched polyethylene." Colloid & Polymer Science 266(1): 29-34.

The application of thermodynamics of eutectoid copolymers and a generalized Tabor-relation to relationships between mechanical properties (microhardness, yield stress) and microstructure in semicrystalline polymers is considered. The approach is illustrated by results on melt-crystallized low density polyethylene, investigated near the yield point at different temperatures. The success of the approach emphasizes that semicrystalline polymers, despite being viscoelastic heterogeneous systems, give rise to a yielding process entailing the irreversible deformation of a larger number of crystals within cooperative super-structure units. Microhardness provides, within this context, a unique measure of the crystal size average. Comparison of calculated and experimental data favors the view of deformed crystals containing basal defective surface boundaries ('meso-crystals') which yield cooperatively. (22 References).
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[290] Fromherz, P., Oelschlagel, U. and Wilke, W. (1988). "Medium angle X-ray scattering of Langmuir-Blodgett films of cadmium salts of fatty acids." Thin Solid Films 159: 421-7.

Langmuir-Blodgett films of cadmium salts of fatty acids from cadmium myristate to cadmium lignocerate were studied by X-ray diffraction. The thickness of a bilayer was obtained from model calculations of the scattering intensity. The bilayer thickness increases linearly with the chain length, indicating isomorphic packing for all salts, with an inclination of the chains of about 15 degrees . The effective electron density in the plane of cadmium exceeds the stoichiometry of cadmium (acid, 1:2). A perfect fit of the intensity data on the basis of a unit cell of a reverse bilayer was not attained. (13 References).
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[291] Marti, O., Drake, B. and Hansma, P. K. (1987). Atomic force microscopy of liquid-covered surfaces: atomic resolution images. Santa Barbara, CA, USA, University of California, Santa Barbara: 14
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[292] Marti, O., Drake, B. and Hansma, P. K. (1987). "Atomic force microscopy of liquid- covered surfaces: Atomic resolution images." Applied Physics Letters 51( 7): 484-486.
marti_7.pdf  
Images of graphite surfaces that are covered with oil reveal the hexagonal rings of carbon atoms. Images of a sodium chloride surface, protected from moisture by oil, exhibit a monoatomic step. Together, these images demonstrate the potential of atomic force microscopy (AFM) for studying both conducting and nonconducting surfaces, even surfaces covered with liquids. The authors' AFM uses a cross of double wires with an attached diamond stylus as a force sensor. The force constant is approximately=40 N/m. The resonant frequency is approximately=3 kHz. The lateral and vertical resolutions are 0.15 nm and 5 pm.
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[293] Marti, O., Binnig, G., Rohrer, H. and Salemink, H. (1987). "Low-temperature scanning tunneling microscope." Surface Science 181: 230-234.
marti_6.pdf  
A scanning tunneling microscope operating at cryogenic temperatures is described. Results from topographic and spectroscopic measurements are presented for surfaces of NbN and graphite at a temperature of 6.5 K. A unique feature of this system is the very low spatial drift and the resulting high positional stability. The topographical data on NbN display a grainy structure. No indications for a superconductive energy gap are found from the tunnel spectroscopy. In the ordered graphite structure, domains are found separated by dislocations.
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[294] Stoll, E. P. and Marti, O. (1987). "Restoration of Scanning-Tunneling Microscope Data Blurred by Limited Resolution, and Hapered by 1/f like noise." Surface Science 181: 222.
marti_5.pdf  
Least-squares or Wiener filters are powerful tools to restore blurred and noisy pictures. For an optimal implementation, a knowledge of the noise and of the point-spread function (PSF) is needed; whereas the resolution PSF is relatively well known from recent theories of STM, the noise spectrum can be investigated by recording and analyzing the signal of the feedback which should keep the tunneling current constant. A 1/fbeta noise spectrum is found with beta =1.4+or-0.2. This noise can give rise to pretended hills and valleys or to spurious stripes parallel to the scanning direction in STM images. With a Wiener filter, in which the model noise-to-signal ratio is 1/fbeta -like these artificial features are eliminated. However, since the noise spectrum may partly overlap the desired spectrum of the surface corrugation, care has to be taken not to generate new artifacts.
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[295] Marti, O. (1987). Scanning tunneling microscope at low temperatures. Physics. Zürich, Switzerland, ETH (Federal Institute of Technology): 168
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[296] Kruger, J. K. and Pietralla, M. (1987). "Evidence for transition-like phenomena in oligomers and polymers above their melt transition." Order in the Amorphous 'State' of Polymers. Proceedings of the 17th International Symposium. Plenum..

The evidence for a liquid-liquid transition in the melts of oligomers and polymers which are able to crystallize is summarized. The emphasis, with respect to experiments, lies on Brillouin Spectroscopy (BS). The transition is indicated by a step-like change of several physical properties at a well-defined temperature named T/sub u/. Hypotheses about this transition are discussed in the light of recent experiments. (36 References).
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[297] Gerber, C., Binnig, G., Fuchs, H., Marti, O. and Rohrer, H. (1986). "Scanning tunneling microscope combined with a scanning electron microscope." Review of Scientic Instruments 57: 221-224.
marti_4.pdf  
We have developed a small scanning tunneling microscope (STM) to be incorporated into a scanning electron microscope (SEM). Vibration isolation and damping is achieved solely with Viton dampers. As a stand-alone unit, a tunnel-gap stability of about 1 Å is reached at atmospheric air pressure without additional sound protection. Stability improves by at least an order of magnitude when incorporated into a SEM. Review of Scientific Instruments is copyrighted by The American Institute of Physics
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[298] Ania, F., Kilian, H. G. and Balta Calleja, F. J. (1986). "Recent developments in the understanding of the microhardness of paraffins." Journal of Materials Science Letters 5(11): 1183-5.

The microhardness of materials consisting of lamellar structures with thickness l/sub c/, such as n-paraffins, can be conveniently described through the expression H=w/sub p/H/sub p/=w/sub p/H/sub 0//(1+b/sub 1//l/sub c/), where H/sub 0/ is the hardness of an infinitely thick crystal, w/sub p/ is the molar mass fraction of crystallites and b/sub 1/ approximately=20 nm under 'normal' crystallisation conditions. The range of validity of this equation, with reference to its temperature dependence, is verified for a series of even paraffins ranging from n=20 to n=40. (11 References).
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[299] Gerber, C. and Marti, O. (1985). "Magnetostrictive positionner." IBM Technical Disclosure Bulletin 27: 6373.
marti_3.pdf
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[300] Binnig, G., Gerber, C. and Marti, O. (1984). "Sound and vibration insulation for sensitive apparatus." IBM Technical Disclosure Bulletin 27: 3137.
marti_2.pdf  
The present damping system comprises a stack of copper plates separated by elastic pads, the cross section of which decreases from bottom to top of the stack, forming individual filter stages with differing resonant frequencies acting as an acoustical mismatch
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[301] Ott, H. R., Marti, O. and Hulliger, F. (1984). "Low temperature thermal conductivity of CeAl3." Solid State Communications 49: 1129-1131.
marti_1.pdf  
Measurements of the thermal and electrical conductivity of CeAl3 reveal the validity of the Wiedemann-Franz law in this substance at temperatures below 1K, hence confirming the Fermi-liquid behaviour as implied by previous data of the specific heat and the magnetic susceptibility in this temperature range.
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[302] Kilian, H. G., Hohne, G. W. H., Trogele, P. and Ambacher, H. (1984). "Stretching calorimetry and thermoelasticity of rubbers at different temperatures." Journal of Polymer Science, Polymer Symposia, no 71: 221-30.

The data of isothermal stretching calorimetry on rubbers at different temperatures above room temperature are presented. Based upon the van der Waals equation of state for rubbers calculations can be fitted to the experimental data obtained by simple elongation whereby the thermoelastic behavior is related to a constant thermal expansion coefficient in the unstrained state and to an invariant temperature coefficient of the end-to-end distance of the equivalent freely jointed chain. (17 References).
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[303] Vilgis, T. and Kilian, H. G. (1984). "The van der Waals-network-a phenomenological approach to dense networks." Polymer 25(1): 71-4.

An entangled network model developed by S. F. Edwards is used to identify, in more concrete terms, one of the parameters appearing in a phenomenological van der Waals equation of state. (11 References).
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[304] Blum, K., Kilian, H. G. and Pietralla, M. (1983). "A method for measuring the anisotropy ratio of the thermal conductivity of anisotropy solids." Journal of Physics e Scientific Instruments 16(8): 807-12.

Using the modern methods of radiative temperature measurements a refined De Senarmont method (1848) is developed. It allows the measurement of the anisotropy ratio k/sub 1//k/sub 2/ of the thermal conductivity in different directions 1,2 of an anisotropic solid at room temperature and above. This transient method is especially suited for poor thermal conductors like polymers and does also provide an estimate of the absolute thermal diffusivity. (13 References).
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[305] Kruger, J. K., Hohne, G. W. and Pietralla, M. (1983). "About the transition of n-alkanes above the melting point. Comment to the paper by P. Claudy and J.M. Letoffe." Polymer Bulletin 9: 4-5.

The authors believe the explanation given by Claudy and Letoffe (see ibid., vol.9, p.245-51, 1983) for the high temperature exothermic peak of first DSC runs of n-alkanes is correct but their results do not contradict the present authors' previous explanations (see ibid., vol.2, p.663, 1980 and vol.6, p.41, 1981) of the origin of the T/sub u/ transition temperature. (7 References).
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[306] Vilgis, T. and Kilian, H. G. (1983). "Reduced van der Waals equation of state and critical properties of rubbers." Polymer 24(8): 949-52.

A reduced equation of state describing the deformation mode as simple elongation is derived for van der Waals networks, thus manifesting general relationships for molecular networks also embracing their stability characteristics and the occurrence of a phase transition. (20 References).
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[307] Wilke, W. (1983). "General lattice factor of the ideal paracrystal." Acta Crystallographica Section a Foundations of Crystallography 6(1): 864-7.

The lattice factor of a paracrystalline lattice with oblique axes and with general orientation of the fluctuation tensor ellipsoid is calculated. Directly applicable formulas for the special case of a monoclinic (macro) lattice, which is of interest in connection with the small-angle scattering of oriented semicrystalline polymers, are given. (4 References).
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[308] Kruger, J. K. and Pietralla, M. (1982). "Brillouin spectroscopy of oriented PMMA." Polymer 23(1): 3-6.

The elastic properties of oriented PMMA have been re-investigated by Brillouin spectroscopy. Most of the elastic stiffness tensor components are presented. The order parameter P/sub 2/ has been determined as a function of orientation and is compared with P/sub 2/ deduced from other methods. Previously reported elastic anomalies of oriented PMMA could not be confirmed. (16 References).
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[309] Kruger, J. K., Pietralla, M. and Unruh, H. G. (1982). "The elastic properties of hexatriacontane single crystals at their various phase transitions." Physica Status Solidi A 71(2): 493-504.

For the first time the elastic properties of solution grown hexatriacontane (C/sub 36/H/sub 74/) single crystals are investigated between room temperature and the melt transition by Brillouin spectroscopy. In addition to the transitions reported in the literature a further low temperature phase is found and confirmed by DSC measurements. It turns out that the elastic stiffness in the molecular chain direction is only 11 GPa at 71 degrees C. The temperature dependence of the sound velocity in the rotator phase is brought into connection with the dynamics of kink formation. Elastic properties between room temperature and the melt transition are also reported for melt crystallized pentacosan (C/sub 25/H/sub 52/). (33 References).
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[310] Pietralla, M., Grossmann, H. P. and Kruger, J. K. (1982). "Theoretical birefringence of ultraoriented polyethylene from model structure calculations." Journal of Polymer Science, Polymer Physics Edition 20(7): 1193-205.

The birefringence of model structures of ultraoriented polyethylene has been calculated by using the point-dipole concept and the polarizability tensor of the methylene group. For well-oriented chains the birefringence is determined by the combination of a negative anisotropy of the polarizability tensor of the methylene group and a positive anisotropy of the Lorentz tensor, both with respect to the chain direction. As a consequence it decreases with increasing density. In the model the amorphous regions are regarded as a mixture of planar and helical segments arranged in nematiclike bundles which additionally may have a certain distribution of orientation. The birefringence is not much affected by defects which, on the other hand, strongly influence the ultimate mechanical properties. (16 References).
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[311] Frank, W. F. X., Schmidt, H., Heise, B., Chantry, G. W., Nicol, E. A., Willis, H. A. and Cudby, M. E. A. (1981). "A new far infra-red absorption band at 39 cm/sup -1/ in the spectrum of high-pressure crystallized polyethylene." Polymer 22(1): 17-19.

High-pressure annealed samples of polyethylene (PE), currently thought to contain the extended chain form, show a new band at 39 cm/sup -1/ in the absorption spectrum when the sample temperature falls below 170K. This band shows a strong temperature dependence of intensity but no shift in frequency as the temperature varies. Possible assignments of the band are discussed. The preferred interpretation, with some reservations, is that it arises from a mode analogous to the forbidden A/sub u/ mode of orthorhombic PE but which is now active in the monoclinic form produced by the annealing. (14 References).
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[312] Kilian, H. G. (1981). "Equation of state of real networks." Polymer 22(2): 209-17.

The effects of mutual interactions between the chains of a molecular network are taken into account by a van der Waals approach for an 'ideal conformational gas'. The utility of the new equations of state can be judged by their ability to describe the results of a set of different known experiments. Thus, it is shown that the retractive force of a real network seems to be not only intramolecular in its origins. (40 References).
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[313] Kruger, J. K., Peetz, L., Pietralla, M. and Unruh, H. G. (1981). "Brillouin spectroscopy at the melt transition of poly-4-methyl-penetene-1: Discontinuous melting of superstructures?" Polymer Bulletin 4(10): 591-6.

The elastic properties of poly-4-methylpentene-1 around the melt transition hve been studied by Brillouin spectroscopy. A discontinuous change of the sound velocity is observed in the melting region of 10K indicating a rather discontinuous melting and formation of spherulites with sharp boundaries. Another results is that practically the final elastic properties of the spherulites appear already during their formation. (11 References).
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[314] Kilian, H. G. (1980). "A molecular interpretation of the parameters of the van der Waals equation of state for real networks." Polymer Bulletin 3(3): 151-8.

A molecular interpretation of the phenomenological van der Waals parameters of the equation of state for real molecular networks is presented. The theoretical treatment is elucidating the special role of the crosslinks. (9 References).
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[315] Kruger, J. K., Bastian, H., Asbach, G. I. and Pietralla, M. (1980). "The elastic properties of C/sub 36/H/sub 74/ single crystals from Brillouin-Spectroscopy." Polymer Bulletin 3(12): 633-40.

The elastic properties of C/sub 36/H/sub 74/ single crystals have been investigated at room temperature by Brillouin spectroscopy. A nearly complete set of data is presented for the crystallographic (a,b)-plane. Furthermore the longitudinal sound velocity normal to that plane could be determined. (13 References).
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[316] Pietralla, M. (1980). "Internal field of polymer crystals: polarizability tensor of the methylene group from the birefringence of paraffin crystal." Journal of Polymer Science, Polymer Physics Edition 18(8): 1717-35.

Using the concept of a point dipole lattice, it is shown that the internal field of induced dipoles can be calculated for crystals comprised of simple chain molecules. The only structure which must be taken into account accurately is that of the chain molecule itself. From the calculations, reliable values of the polarizability tensor of the CH/sub 2/ unit are deduced from the birefringence of the paraffin crystal. In addition, it is shown that birefringence measurements provide a method for demonstrating the consistency of polarizability data so that no detailed structural information is needed. For the CH/sub 2/ unit, it is found by both methods that alpha /sup ///- alpha /sup perpendicular to /=-0.63 with respect to the chain direction (the units of polarizability alpha are 10/sup -24/ cm/sup 3/ (cgs)). The most probable anisotropics for the bond polarizabilities are alpha /sub CH//sup ///- alpha /sub CH//sup perpendicular to /=0.30, alpha /sub CC//sup ///- alpha /sub CC//sup perpendicular to /=-0.62. (36 References).
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[317] Pietralla, M. and Kilian, H. G. (1980). "Birefringence of stretched polyethylene and its relation to changes in structure." Journal of Polymer Science, Polymer Physics Edition 18(2): 285-90.

It is shown that the birefringence of a polyethylene crystal can be severely shape dependent via the internal field. Using the cluster model it is concluded that this dependence plays an important role in the structural transition in the uniaxial stretching process. (14 References).
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[318] Kilian, H. G. and Maier, E. (1979). "Thermodynamics of swollen, partially crystallized pseudoeutectoid copolymers of ethylene." Journal of Polymer Science, Polymer Physics Edition 17(9): 1531-46.

It is concluded that swelling phenomena within partially crystallized linear copolymers of ethylene with randomly distributed noncrystallizable co-units can be described by the thermodynamics of deformed cluster networks, the formulation of which is based on an earlier description of the melting of pseudoeutectoid copolymers. (23 References).
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[319] Frank, W., Goerke, K. and Pietralla, M. (1978). "Demonstrating Fourier transform spectroscopy for students." Applied Optics 17(9): 1413-17.
Pi_1978.pdf  
Theory of an ideal Michelson interferometer is described. The instrument designed has a 230 mm mirror displacement and measures line profiles, distinguishing between Doppler and pressure broadening. (6 References).
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[320] Kilian, H. G. and Klattenhoff, D. (1978). "The quasi-static modulus of partially crystallized copolymers of ethylene at small strains." Progress in Colloid & Polymer Science 64: 303-14.

Transferring the basic principles of the theory of rubber elasticity of a Gaussian network, an analogous description of crystal-networks is presented. The quasistatic moduli of various random copolymers of ethylene can also be computed quantitatively using a thermodynamic theory of melting. The results yield classification of the deformation mechanism at small strains in partially crystallized polymer systems with different degrees of crystallinity. (36 References).
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[321] Kilian, H. G. and Pietralla, M. (1978). "Anisotropy of thermal diffusivity of uniaxial stretched polyethylenes." Polymer 19(6): 664-72.

The authors have measured the dependence of the anisotropy ratio A= alpha /sub //// alpha /sub perpendicular to / of thermal diffusivity (at 300K) of polyethylene on the draw ratio, using a point source method. As crystallinity increases the anisotropy increases with the draw ratio. The measurements can be described with the aid of the well known aggregate model using the orientation parameters of the crystals as determined by X-ray methods which are not following an affine deformation assumption. Only one additional parameter is needed, the intrinsic anisotropy of a stack composed of alternating crystalline and amorphous lamellae. These stacks are regarded as the sub-units of deformation. The extrapolation of the intrinsic anisotropy yields reasonable results of A approximately=2 for the completely amorphous, and A approximately=50 for the completely crystalline polymers, respectively. (23 References).
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[322] Kruger, J., Peetz, L. and Pietralla, M. (1978). "Brillouin scattering of semicrystalline poly(4-methyl-1-pentene): study of surface effects of bulk and film material." Polymer 19(12): 1397-404.

Partially crystalline but highly transparent poly(4-methyl-1-pentene) has been investigated as bulk and film material by Brillouin scattering. Special surface effects have been demonstrated in terms of elastic compressional and shear constants. The temperature dependence of the hypersonic velocity has been studied between 17 and 350K indicating a glass transition temperature of 288K. (17 References).
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[323] Meyer, H. and Kilian, H. G. (1978). "The one-dimensional characterization of the microstructure of melt-crystallized polymer systems." Progress in Colloid & Polymer Science 64: 154-65.

Inasmuch as the micr-structure of melt-crystallized polymer samples may be represented by a cluster ensemble, it can be demonstrated by theory (linear paracrystal) and experiment (SAXS light-diffraction experiments using electron-micrographs as objects) that allowance can be given for a one-dimensional characterization of the small-angle X-ray intensity functions referring to the longitudinal structure only, without taking the lateral dimensions into consideration. (19 References).
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[324] Meyer, H. and Kilian, H. G. (1978). "The one-dimensional synthesis of the small-angle scattering pattern of high-density polyethylene." Progress in Colloid & Polymer Science 64: 166-73.

Adhering to the one-dimensional characterization of small angle X-ray pattern of melt-crystallized high density polyethylene with the aid of the one-dimensional paracrystalline theory the authors arrive at the model of a heterogeneous microstructure represented by a cluster ensemble with locally fluctuating average distances of neighbouring crystal lamellae. These characteristics can be verified from stained electron micrographs the rotated light-diffraction pattern of which are in excellent agreement with the SAXS-pattern. Moreover, the slope of caloric measurements (c/sub p/ (T)-curves) on well-annealed HDPE samples can quantitatively be computed employing the crystal-thickness distribution gained from the synthesis of the SAXS-pattern. (28 References).
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[325] Heise, B., Kilian, H. G., Lupke, G., Shulz, P., Woebcken, W. and Zohren, J. (1972). "Crystallite orientation in injection-moulded polyethylene specimens." Kolloid Zeitschrift und Zeitschrift Fuer Polymere 250(2): 120-32.

The degree of crystallite orientation in quarter-disks of low-pressure polyethylene was determined by X-ray diffraction, coloured and uncoloured specimens, and specimens of various thickness (1 mm-4 mm) being examined. The orientation was found to be related to the temperature and pressure of preparation, and to the nature of the colouring material. The shrinkage properties of the specimens were found to be related to the thickness and to the orientation. (14 References).
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[326] Brunner, R., Stifter, T. and Marti, O. Verfahren zur Bestimmung des Abstandes einer Nahfeldsonde von einer zu untersuchenden Probenoberfläche und Nahfeldmikroskop. Japan, ZeissTo top

[327] Brunner, R., Stifter, T. and Marti, O. Verfahren zur Bestimmung des Abstandes einer Nahfeldsonde von einer zu untersuchenden Probenoberfläche und Nahfeldmikroskop. USA, ZeissTo top

[328]
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[329] To top