Mean recombination time of diffusion controlled geminate reactions

A recently introduced method by Deutch for determining the mean passage time for diffusion controlled processes [J. Chem. Phys. 73, 4700 (1980)] has been further developed for application to the reactions of geminate pairs. First, a nonzero probability of escaping geminate recombination requires a normalized definition of mean recombination time which is done consistently. Second, only a finite dose results in a finite mean reaction time. Adopting a special outer boundary condition related to the dose, mean recombination times are calculated for ionic and neutral geminate reactions. For application in radiation- and photochemistry, fully and partially diffusion controlled conditions are applied to ionic and neutral cases, respectively.