EXCLUDED-VOLUME EFFECTS IN PHOTOINDUCED ELECTRON-TRANSFER AND GEMINATE RECOMBINATION - ANALYTICAL THEORY AND SIMULATIONS

Analytical theory and Monte Carlo (MC) simulations are used to examine the problem of photoinduced electron transfer and geminate recombinat ion in both infinite three-dimensional systems and in restricted geome try systems. As an example of a restricted geometry system, donor and acceptor molecules on the surface of a spherical micelle are considere d. The analytical theory is an exact treatment for fixed donors and ac cepters when the distance dependence of the transfer rate falls off ex ponentially and donor-acceptor excluded volume (DA EV) is included. Co mparisons to the MC simulations, which include DA EV, show perfect agr eement for both the 3D system and the micelle system. However, compari sons of the analytical theory to the simulations show that for suffici ently high acceptor concentration, acceptor-acceptor excluded volume ( AA EV) becomes important. With AA EV, the analytical theory is no long er exact. A new approximate method for the inclusion of AA EV in the a nalytical theory is described. Comparisons with the simulations show t hat it is accurate up to substantial concentrations, but at sufficient ly high acceptor concentrations, significant deviation from the MC sim ulation results are seen.