Solvation structure and the time-resolved Stokes shift in non-Debye solvents

We develop a microscopic theory of the time-resolved Stokes shift of a chromophore in a polar solvent which incorporates both non-Debye dielectric relaxation and solvation shell structure. The present theory depends on the direct correlation function of the pure solvent, the measured frequency-dependent dielectric constant, and a microscopically derived translational diffusion parameter. We compare the predictions of the theory given here to a variety of experimental results on solvation in protic and aprotic solvents. Good agreement with experiment is found. Our theory compares favorably with the dynamical mean spherical approximation (MSA) theory of time-dependent solvation.