Observation of Slow Vibrational Relaxation in Halogenated Benzene Radical Cations in Rare-Gas Solids

Abstract

Fluorescence originating from various excited vibrational levels of the $\tilde{B}$ electronic state of several halobenzene cations in solid Ne matrix has been observed and analyzed. The spectra show clearly the Jahn-Teller splitting in the ground electronic state and give for the first time information about the magnitude of the quadratic coupling terms. Excitation spectra of the unrelaxed emission give insight into the dynamics of relaxation and suggest it is a highly nonstatistical process.