Dependence of the recombination kinetics of geminate electron-ion pairs on the mean free path of electrons

Abstract

We have investigated how the kinetics of geminate recombination of electron-ion pairs is influenced by the mean free path of electrons. By use of the Monte Carlo method previously developed the decay of the pair survival probability was numerically calculated for a variety of values of the mean free path of electrons. When the mean free path is negligibly small compared with the Onsager length, our result is in good agreement with the Hong-Noolandi result based on the Smoluchowski equation. However, as the mean free path increases, it deviates from their result increasingly. This indicates that the treatment based on the Smoluchowski equation is inadequate when the mean free path of electrons is not negligible compared with the Onsager length. We have found that for mean free paths comparable with or larger than the Onsager length the decay kinetics of the pair survival probability approximately follows the first-order kinetics except at very short and very long times. The dependence of the escape probability on the mean free path of electrons is also briefly discussed.