Dynamics of intramolecular vibrational-energy redistribution (IVR). I. Coherence effects

Abstract

In this series of papers, theoretical and experimental results concerning the dynamical manifestations of intramolecular vibrational‐energy redistribution (IVR) in temporally resolved fluorescence are presented. In this paper (I) we present a general treatment of IVR and coherenceeffects in multilevel vibrational systems. Specifically, the concern is with the derivation of the characteristics of the beat‐modulated fluorescence decays which arise from vibrational coupling among N levels within a molecule. Relations connecting quantum beat frequencies, phases, and modulation depths to coupling parameters are presented. Likely sources of deviation of experimental results from theoretical predictions are considered. And, finally, the direct link between IVR and time‐resolved fluorescence experiments is discussed with emphasis placed on the physical interpretation of vibrational quantum beats and the nature of IVR as a function of vibrational energy in a molecule.