Femtosecond IR Studies of Solvation by Directly Probing the Solvent

Abstract

The response of solvent to the change of charge or dipole of solute molecules has been intensely studied in recent years1. In previous solvation experiments, time dependent fluorescence Stokes shift of dye molecules in different solvents were measured, from which the solvation time for the solvents were determined1,2. Various theories, from the simple dielectric continuum model to instantaneous solvent normal mode analysis, have been used to relate solvent motions to solvation time3,4. MD simulations have also been carried out to understand the nature of these solvent motions in the solvation process5. However, these time dependent Stokes shift experiments, which measure the solute fluorescence, can only provide an indirect microscopic picture of the relevant solvent motions during the solvation process.