Dynamical solvent effects in liquid phase chemical reactions. Reactions in solvents with several polarization relaxation times

Abstract

The theory of isomerization and charge transfer reactions developed by van der Zwan and Hynes is generalized to the case of solvents with several relaxation times of medium polarization. Expressions for the rate constant of reaction are found for a few limiting cases. It is shown that if large solvation forces act from the solvent on the dipole under isomerization or on the transferring charge the rate constant of the reaction is determined by the longest dielectric friction relaxation time. If weak solvation forces act on the dipole or the charge the reaction rate strives with the increase of friction relaxation times for the limit which is fully independent from relaxation times. When the solvation forces have frontier values the rate constant of the reaction decreases with the increase of relaxation times by a power law much more slowly than the Kramers theory predicts.