Temperature Dependence of Specific Rates of Benzene Monomer and Excimer Fluorescence

Abstract

The specific rates which describe the fluorescence behavior of benzene have been determined from lifetime measurements of excited benzene in methylcyclohexane solution in the temperature range 169–298°K. Particular attention is directed to the rates at 195°K, because at this temperature the rates for excimer association and dissociation can be directly measured by pulse techniques described. It is confirmed that excimer is formed at a diffusion‐controlled rate, but it is also found that excimer dissociation proceeds more rapidly in dilute solutions than in concentrated solutions of benzene. Specific rates of fluorescence for both monomer and excimer are found to have the same temperature dependence on change from 298 to 195°K, although the magnitudes of the rates differ. Refined values of other specific rates have also been obtained and, when comparison can be made, have been shown to have the same value in solution as in the vapor phase at pressures of several torr or above.