Inorganic glasses prepared by the 'cold' chemical sol-gel process can present an alternative host material for
organic fluorescent dyes. We report on measurements done on thin Si02 layers prepared as sol-gels and doped
with various dyes on a glass substrate. The preparation is done by dip-coating of the substrate in the corresponding
alcoxide solutions. Good quality layers without crazing after drying are achieved with a thickness of up to 1-2
microns.
The measurements include absorption measurements (UV to IR), fluorescence and excitation measurements
(visible to NIR), and measurements of photo-decomposition. The optical properties of the dye molecules in the
layer and in the sol-gel solutions are studied as a function of dye concentration and changes in the thermal treatment
of the layers. The results are examined for their applicability to FPC's.
Further we report on small silver islands (submicron size) brought into the sol-gel solution as stabilized
colloids or by chemical reduction of Ag+ salts. According to theoretical predictions, the electromagnetic interaction
of silver surface plasmons and dye molecules can result, under certain conditions, in an enhanced
fluorescence quantum efficiency and photostability of the dye.
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