Reversible electron transfer in photochemistry and electrochemistry

A complete set of integral equations is used to describe the kinetics of re versible photoionization after instantaneous excitation, including geminate and bimolecular charge recombination, to either the ground or excited stat es of neutral products. The normalized distribution of ionization products, calculated taking into account reverse electron transfer, differs from tha t for irreversible photoionization. At low reorganization energy and slow d iffusion, the reversibility of the quasiresonant ionization reduces its qua ntum yield, but does not affect the charge separation quantum yield. The ex citations restored by bimolecular recombination of ions produce the delayed fluorescence which goes to zero as a second power of time. The quantum yie ld of the electroluminescence detected after injection of ions into solutio n has a sharp free energy dependence, like that observed experimentally. (C ) 2001 American Institute of Physics.