Influence of non-Debye relaxation and of molecular shape on the time dependence of the stokes shift in polar media

Abstract

We present theoretical analyses of two different aspects of the time dependence of the fluorescence Stokes shift in polar liquids. We show that a small deviation from the Debye form for the dielectric relaxation of the solvent can strongly influence the time evolution of the Stokes shift. Using the Davidson-Cole form for dielectric response we find a stretched exponential time dependence as observed in recent experiments. We also show that the shape of the fluorescing molecule can influence the dynamics of solvation.