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Intramolecular vibrational relaxation of CH stretch overtones in benzene

1987; American Institute of Physics; Volume: 86; Issue: 8 Linguagem: Inglês

10.1063/1.452712

1520-9032

Karen L. Bintz, Donald L. Thompson, John W. Brady,

Quantum, superfluid, helium dynamics

Energy flow from CH overtones in benzene has been examined using quasiclassical trajectory calculations. The potential energy surfaces for this study are of the form reported by Pulay, Fogarasi, and Boggs [J. Chem. Phys. 74, 3999 (1981)]. The effect of out-of-plane motion on energy transfer in benzene was examined by comparing results for planar and nonplanar models. The methods of analysis include the calculation of the energy in each of the CH bonds and the energy in each of the planar normal modes as a function of time. It is shown that there are two distinct sets of normal modes: low frequency modes which do not significantly participate in energy redistribution and higher frequency modes which appear to be strongly coupled to the excited CH bond. Within the participating set of modes, those which appear to possess the most CCH bend character are the most instrumental in absorbing energy from the excited CH bond. This study shows that rapid energy transfer out of an excited CH stretch mode can occur for a purely harmonic potential-energy surface.