Interplay of geminate and bimolecular reactions in multistage electron and energy transfer

Within the universal integral formalism of encounter theory, we described (a) the bimolecular charge recombination that follows the geminate one beginning with photoionization and (b) bimolecular quenching of singlet and triplet excitations parallel to an inter-system crossing (ISC). In both cases the new features appear which represent either the geminate ion pair density (positive) or pair vacancies density (negative), which accounts for singlets quenched before ISC. It was justified that the shortage of near-contact excitations resulting from static singlet quenching may be built into the initial conditions for subsequent evolution of triplets and lead to the ''anti-Smoluchowski time behavior'' of their annihilation rate constant. However, only an integral theory can account for the same effect when singlet quenching is diffusion accelerated, (C) 1997 American Institute of Physics.