Primary photophysical processes in phenylcyclohexane

Abstract

The fluorescence spectra and measured lifetimes of the first excited singlet state of phenylcyclohexane have been determined as a function of concentration and temperatue. The binding energy of the phenylcyclohexane excimer is found to be 0.27 (± 0.03) eV. Triplet yield measurements on 0.12 M solutions in cyclohexane as a function of temperature have been made between 30 and 60°C. The activation energy and pre-exponential factor for the radiationless S₁→S₀ decay are 0.26 (± 0.03) eV and 4.7 (± 0.5)× 10¹¹ s^–1. The intersystem crossing process is slightly temperature dependent in the range studied. The results are compared with those for benzene, determined previously, and their significance discussed qualitatively on a symmetry basis.