Radiationless Deactivation of the Fluorescent State of Substituted Anthracenes

Abstract

Radiationless deactivation of the fluorescent state of substituted anthracenes has been studied by measuring the temperature dependence of both the triplet yield and the absolute fluorescence lifetime. It is concluded that in those derivatives which show a significant variation of fluorescence yield with temperature, radiationless deactivation proceeds entirely by intersystem crossing. The existence of triplet states which are approximately degenerate with the fluorescent state in anthracene derivatives has been demonstrated experimentally. A tentative explanation is offered for the influence of temperature and substitution on the fluorescence behavior of substituted anthracenes.