THE EXTERNAL HEAVY-ATOM SPIN ORBITAL EFFECT ON INTER-SYSTEM CROSSING

Abstract

“The relative phosphorescence to fluorescence quantum yields and phosphorescence lifetimes of naphthalene have been measured in a number of glassy media, some of which contain perturbing atoms of large atomic number. It is shown that the intersystem-crossing process is the most sensitive to environmental spin-orbital coupling effects. The phosphorescence-quenching process is less sensitive than the intersystem-crossing process, but more sensitive than the phosphorescencemission process. It is strongly suggested by the data contained herein that heavy-atom quenching of fluorescence can indeed be attributed primarily, if not entirely, to increase in the probability of the intersystem-crossing process. A number of possible uses for the heavy-atom technique are suggested.”