Bridge-assisted electron transfer driven by dichotomically fluctuating tunneling coupling

Abstract

The influence of dichotomically fluctuating tunneling coupling on long-range electron transfer is studied theoretically. Within an approach similar to the noninteracting blip approximation known from the spin-boson model a set of coupled integrodifferential kinetic equations is derived. These equations describe the time development of the electronic populations difference between the donor and acceptor states averaged with respect to the stochastic process and the quantum fluctuations of the bath. Furthermore, they contain the correlator between the level population difference and the fluctuating tunneling matrix element. A detailed analysis is carried out for the case of a strong coupling of the transferred electron to a single soft reaction coordinate. Within a Markovian approximation and an adiabatic removing of the correlator, the balance type kinetic equations can be derived which contain effective transfer rates. These rates depend strongly on the correlation time of fluctuations and can exhibit a resonancelike behavior. © 1995 American Institute of Physics.