Heavy atom effects on geminate and free radical recombination

Abstract

The free radical yield and the rate constants of triplet quenching and free radical recombination were investigated in acetonitrile for the triplet acriflavine—para-halogenated aniline system. The yield decreases as the atomic number of the halogen substituent increases, whereas the rate constant of free radical recombination increases. The rate constant of triplet quenching does not differ between para-halogenated anilines. These heavy atom effects are interpreted in terms of spin—orbit coupling between the triplet radical pair and the singlet ground states.