Radiationless Transitions and Deuterium Effect on Fluorescence Lifetimes of Some Aromatic Hydrocarbons

Abstract

The fluorescence lifetimes of several perprotonated and perdeuterated aromatic hydrocarbons have been measured in rigid media at 77°K. Within experimental error, no change is found in lifetime upon substitution of deuterium for protium. It is concluded from this result that radiationless first excited singlet to ground singlet (S1→S0) transitions are unimportant in these systems. The fluorescence lifetime of anthracene at room temperature also compares favorably with that at low temperature, suggesting strongly that S1→T1 (first excited singlet to lowest triplet) radiationless processes in aromatics are temperature independent.