Electron transfer in the inverted region: Adiabatic suppression and relaxation hindrance of the reaction rate

Abstract

Kramers’s model is applied to an electron transfer reaction in the inverted region. The reaction rate is considered at different values of the coupling matrix element and the damping, which is a measure of the interaction of the reaction coordinate with the other, nonreactive degrees of freedom of the system. The coupling characterizes overlap of the electron orbits of the donor and acceptor. It is shown that at the low/high damping the reaction rate is controlled by the slowest of the two rates. One is the thermally averaged transition rate (the reaction rate in the intermediate damping regime) and another one is the rate controlled by the energy/spatial diffusion. We demonstrate that the reaction rate as a function of the electron coupling shows a striking difference from the normal region case. The rate passes via maximum and decreases exponentially with the increase of the coupling.