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Soft biological samples
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Optische Nahfeldmethoden zur Erkennung einzelner Moleküle
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SNOM on soft biological samples

Topography and fluorescence images of a growth cone of nerve cells of thehippocampus of rat. The samples are fluorescence labeled with DIC18, showing an absorption peak at 540 nm and an emission maximum at 570 nm. The sample was excited with an argon ion laser (l = 514 nm) at a power of about 5nW, as measured in the far field of the tip.(Samples courtesy of P. Fromherz, MPI Martinsried)

SNOM on semiconductor samples

   Near-field microscopy: VCSELs

Shear force distance regulation

   A glass substrate (hydrophillic), partially covered with Langmuir -Blodgett film of arachidic acid (hydrophobic) was used to measure the influence of different relative humidities on shear-
force distance regulation, usually used in near-field optical microscopy. At low relative humidities (left), the contaminating water layer is very thin and height difference between glass
substrate and LB-film is nearly as high as expected from x-ray experiments. At higher humidities (right), the height difference decreases, due to a growing water layer on the glass substrate.
The height difference between both pictures is 0,6nm,corresponding to 2 layers of water molecules. (Sample courtesy of P. Fromherz et al., MPI Martinsried)

SNOM on polymers

   Topography and fluorescence images of coloured polymer blends PS/PMMA. The polymers were
spin coated on a glass substrate from a dyed (R6G) solution. R6G is good soluble in PMMA, but
only slightly soluble in PS. With AFM techniques, a distinction between both polymers would hardly
be possible, especially if the surface is totally covered by one polymer, as shown in the pictures
below.
   Topography and fluorescence images of coloured polymer blends (PS/PMMA 50/50). The polymers
were spin coated on a glass substrate from a dyed (R6G) solution. R6G is good soluble in PMMA,
but only slightly soluble in PS. The dewetting structures are very sensitive to the molecular weights
of the polymers.
  Topography and fluorescence images of spherolytes in polypropylene. The spherolytes were grown from solution.The dye is not soluble in the crystalline and amorphous regions of the spherolytes and is only visible in the grain boundaries.

 

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Last modified: 30. Juli 1999