An approach to the lsquo;lsquo;channel threersquo;rsquo; phenomenon of benzene

摘要

The nonradiative decay of benzene excited within theS1manifold is studied by assuming an open vibrational potential for theS2state that leads to spontaneous breaking of hexagonal symmetry along a path for valence isomerization. TheS2state crosses theS1electronic configuration (at the channel three threshold) as well as the ground state along the reaction path. The rate constants of nonradiative decay of theS1state (in fact theS1uS2internal conversion) and theS2state (S2uS0IC) are both quantum mechanically calculated by invoking microcanonical averaging over all vibrational levels accessible at a given excess of vibrational energy. The results obtained account for a number of features observed in spectroscopy of benzene at the channel three threshold.