Molecular fluorescence and near resonance Raman yield as a probe for solvation dynamics

Abstract

A microscopic theory for spontaneous emission line shapes of polyatomic molecules in condensed phases is developed. The distinction between the Raman and the fluorescence component is discussed and a rigorous transform relation between the total Raman excitation profile and the absorption line shape is obtained. The effects of solvation are introduced via generalized solvent line shape functions corresponding to the solvent dynamics before and after the reorganization process which follows the electronic excitation. The Raman yield and its frequency dependence are shown to provide a sensitive probe for the solvent dynamics. Detailed calculations for model systems and for the retinal chromophore in bacteriorhodopsin are presented.