FACTORS CONTROLLING THE EFFICIENCIES OF PHOTOINDUCED ELECTRON-TRANSFER REACTIONS

The overall efficiencies of photoinduced electron transfer reactions i n polar solvents are usually determined by the efficiency with which s eparated radical ions are formed from the initially formed geminate ra dical-ion pairs. These separation efficiencies are determined by the c ompetition between return electron transfer and separation within the geminate pairs. A method is described for determining whether variatio ns in the quantum yields for formation of separated radical ions are d ue to changes in the reorganization parameters for the return electron transfer reactions, or to other factors. The use of the method is ill ustrated in studies of the effects of varying steric bulk and molecula r size of the donors, and also in studies of the effect of using a cha rged sensitizer.