MAGNETIC EFFECTS ON TRIPLET EXCITON INTERACTIONS

The rates of many bimolecular reactions involving triplet excitons are magnetic field dependent at room temperature and for modest field strengths. The specific interactions discussed are the fusion of a pair of triplet excitons to yield either a single or triplet exciton, the interaction between a triplet exciton and a trapped triplet, the fission of a singlet exciton into a pair of triplets and the triplet exciton— free radical interaction. The magnetic field effects result from the influence of the field on the spin wavefunctions of the triplet exciton together with the existence of spin selection rules for the interactions. A simple theory of these effects is presented. Application of the theory to the experimental field de-pendence results yields new information about the mechanisms of these inter-actions. I