Fluorescence Lifetimes of Vibronic States of Benzene in the Vapor Phase

Abstract

The time dependence of benzene vapor fluorescence is studied as function of vapor pressure for excitation in the neighborhood of 2600, 2530, and 2470 Å. At pressures above about 20 torr the decay appears exponential and independent of excitation wavelength. At lower pressure, deviations from exponential decay are observed for 2530- and 2470-Å excitation. The decay times obtained under different conditions are combined with steady-state data available in the literature and several rate constants derived. The result is related to discussions of the mechanism of deactivation of excited benzene molecules.