Kinetic and diffusional control of geminate recombination

A study is presented of geminate recombination and separation kinetics and their rates in liquid solutions. Applicability limits are proposed for the ‘‘exponential model’’ of this process, which is widely used for interpreting experimental data on back-electron transfer following photoionization. It is proved that this model qualitatively contradicts an analytical description of the process in polar media. A numerical experiment shows that the exponential model may be used only for nonpolar media of moderate viscosity. In this case the separation rate is linearly connected with the recombination constant and may be used to check the energy gap law characteristic for electron transfer.