MONTE-CARLO SIMULATION STUDY OF RECOMBINATION DYNAMICS IN SOLUTION

A Monte Carlo (MC) simulation study of radical recombination dynamics in solution is presented. Random walks on a three-dimensional lattice are used to simulate the diffusion of radical pairs initially prepared by photolysis. The survival probability as a function of time is calc ulated by the dynamical interpretation of the MC methods. For the dyna mics of radical pairs, the interplay of the geminate and the bulk reco mbinations is important at high concentrations. In most previous simul ations only the dynamics of isolated geminate pairs were considered. I n our simulations such interplay is clearly demonstrated by studying t he intermediate to long time dynamics of many radical pairs. We compar e our results with the predictions of the diffusion and the kinetic th eories to examine the validity of their approximations. For low concen trations, results of the simulations show good agreement with theoreti cal predictions and provide a microscopic basis for understanding the recombination process. But notable deviations are found for high conce ntrations, which can be attributed to the approximations in theoretica l studies. (C) 1996 American Institute of Physics.