Time-correlated single photon counting (TCSPC) near-field optical measurements were made. The aperture size of our prepared aluminum coated fiber optic probe was approximately 50 nm which represents a spatial resolution of lex/ 7 for our UV measurements. Near-field fluorescence decays of poly-(phenylmethyl) silane in solid thin films excited in the range 325-360 nm were obtained and the steady state excitation spectra compared with the excitation spectral information obtained in the far-field. Fluorescence decays showed single exponential lifetimes ranging from 45 to 277 ps which was dependent on the excitation wavelength and the selected near field tip. The proximity of the metal coated tip to the sample may be the reason for the modulation in fluorescence lifetime. We also continue to study the process of energy migration and localization in polymer silane and co-polymer silane derivatives. In summary, we found that the excitation coherence length depended on both the type of subunit substitution, whether electron donating or accepting, and on the population of the substituted group on the polymer silane backbone. The project continues with studies of assemblies of fluorescent molecules.
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