Position dependent deuterium effects on the vapor phase fluorescence lifetimes of tetradeuterophenanthrenes

Abstract

The fluorescence lifetime of phenanthrene and three of its tetradeuterated isomers are measured in the vapor phase under isolated molecule conditions. The lifetimes fall in the order phenanthrene < 1,3,6,8- d 4 < 1,2,3,4- d 4 < 2,4,5, 7- d 4. The possibility that the change in lifetimes is due to a resonance mechanism of intersystem crossing is discussed.