Photophysics of substituted benzenes. Absolute rate constants for singlet radiative and non-radiative decay in the vapour phase

Abstract

Fluorescence decay times for the vapour of several fluoro-, methyl- and trifluoromethyl-benzenes have been determined at various exciting wavelengths and pressures, and absolute rate constants for radiative and non-radiative decay of the first excited singlet states of these compounds calculated. For fluorine substitution, values of the radiative rate constant are greater than those obtained by integration of absorption curves. With increase in photon energy, the non-radiative rate constant increases and, generally, the radiative rate constant decreases in magnitude.