Electron transfer transitions among many electronic states coupled to multidimensional diffusive nuclear modes: A supramolecular triad system

A theory for the electron transfer (ET) transition rates among many electro nic states taking into account multidimensional solvation dynamics is devel oped. An expression for the frequency-dependent ET rate is derived. The det ailed balance principle for the frequency-dependent ET rate is proved for t he first time. The theory is applied to ET which involves more than two ele ctronic states, including the supramolecular triad system. The ET rate whic h depends on solvation timescale in a nonmonotonic way is found in the case where the transfer of an electron occurs from a donor to an acceptor state s through an intermediate state, which is not fully equilibrated during the transfer. We explored the physical condition under which such a mechanism prevails. For this purpose useful approximations for the Green's function o f the Smoluchowski equation in the frequency domain are developed. (C) 1999 American Institute of Physics. [S0021-9606(99)51907-7].