MICROSCOPIC DYNAMICS OF PHOTOPRODUCED GEMINATE MOLECULES IN SOLVENT CAGE

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1.Effects of Quencher Concentration on Bimolecular Reaction Rate in SolutionThe time resolved fluorescence quenching reaction via intermolecular electron transfer for coumarin 151-N,N-dimethylaniline system in anisole has been studies in the broad range of quencher concentrations.The Smoluchowski sink term model was used to fit the experimental decay curves. The random walk method has been used to solve the diffusion equation under the initial conditions derived from the intermolecular portential between fluorescer and quencher. The importance of the "radical distribution function" instead of " random particle distribution" of the quencher molecules, for explanation of the quenching dynamics at earlier times and higher quencher concentrations, is emphasized.2.Photodissociation and Geminate Dynamics of Aminophenydisulfide in SolutionMeasuring picosecond time resolved absorption spectra, the photo-dissociation of p-aminophenyldisulfide and p-aminophenylthiol in various solvents has been investigated. In tens of picosecond delay times a decay of p-aminophenylthiyl radical ascribed to the geminate recombination was observed for p-aminophenyldisulfied in nonpolar solvents. In addition to a slight change in the spectral shape of thiyle radical, the rise of the broad absorption band, which should be assigned to the radical dimer, follows to the geminate recombination.