Lifetimes of single rotational states in the ‘‘channel three’’ region of C6H6

Abstract

Lifetimes of single rotational states in the 14112 vibrational state of benzene, C6H6, at 3412 cm−1 excess energy were measured. The lifetimes depend strongly on the rotational quantum number J and we find them to agree with our recent homogeneous linewidth measurements of the same states. We present a coupling scheme including the coupling of the excited narrow light zero order state with a broadened dark background state. The broadening is due to a fast electronic nonradiative relaxation process typical for a state containing quanta of out-of-plane modes. It is demonstrated that the observed J dependence is due to perpendicular Coriolis coupling in the weak coupling limit. The IVR process resulting from this coupling explains the onset of ‘‘channel three’’ in a natural way without any further mystery states in the model.