Relaxation of average energy and rearrangement of solvent shells in various polar solvents in connection with solvation dynamics: studied by RISM theory

We employ a reference interaction-site model (RISM) theory to estimate the relaxation dynamics of the average energy of solute–solvent systems as well as the time-dependent radial distribution functions of solvents viewed from the solute. The theoretical results indicate that the rearrangement of the second solvent shell is about an order of magnitude slower compared with that of the first shell. We suggest that the slower relaxation of further solvent shells can play a significant role in the dynamic relaxation of the inhomogeneous spectral width, which has been observed in our previous experiments of the time-resolved hole-burning and fluorescence spectroscopy.