Calculations of V−V Transfer Rates in H2 and Comparison with Experiment

• Published in: The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Vol. 113; no. 10; pp. 1995 - 1998
• Main Author: Kelley, J. D
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 12-03-2009
• ISSN: 1089-5639; 1520-5215
• DOI: 10.1021/jp808355y

Recent observations on VV transfer in H2 have shown interesting results. For nonresonant processes, comparison of the experimental rate constants with the results of previous semiclassical calculations, quantum oscillators/classical rotors coupled via classical collisions, showed the theoretical rate constants to be too slow by a factor of 3 or more. The semiclassical rate constant of the resonant VV process (v = 1 + v = 0 → v = 0 + v = 1) was also found to be too slow, by more than an order of magnitude, compared with the experimental rate. Further, the semiclassical model predicted the value of k(1,1→0,2) to exceed that of k(1,0→0,1), but the experimental data shows it to be a factor of approximately 2 less. In this work we employ an accurate interaction potential for the H2−H2 system, and treat both rotation and vibration of the diatoms as coupled quantum-mechanical degrees of freedom. These new calculated results are in better overall agreement with the near-resonant experimental values, but the calculated rate constants are a factor of 2 to 3 larger than experiment for the nonresonant processes