EFFECTS OF DIFFUSION ON GEMINATE CHARGE RECOMBINATION

Diffusion effects on geminate charge recombination are investigated fo r intermolecular electron transfer system. Analytical and numerical ca lculations are presented for reaction-diffusion equations. In some lim iting cases of the equations, a condition is established where the pop ulation of geminate ion pairs decreases exponentially by charge recomb ination. This condition is that the ion pairs are produced inside the zone of recombination and charge recombination takes place before ion pairs diffuse into separated ions. Numerical calculations are made in realistic cases where reorganization energy in the expression of the r ate constant depends on the reactant distance. As a result, we found t hat the population of ion pairs has both components of exponential dec rease and a root inverse tail (t(-1/2)). The component of exponential decrease is large when the recombination rate is fast.