Further insight into the tunneling contribution to the vibrational relaxation of NO in Ar.
Tunneling corrections to Landau-Zener rate coefficients for the vibrational relaxation NO(X(2)Π, v = 1) + Ar → NO(X(2)Π, v = 0) + Ar between 300 and 2000 K are determined employing ab initio potential energy surfaces calculated by the code provided by Alexander [J. Chem. Phys. 111, 7426 (1999)]. The calculations use a reaction coordinate approach and lead to vibronically nonadiabatic transition probabilities within the generalized Airy approximation as extended to the WKB underbarrier Landau-Lifshitz limit. The calculations confirm experimental evidence for an onset of major tunneling contributions to the relaxation rate at temperatures below about 900 K and rationalize large tunneling contributions at 300 K. These effects increase the rate coefficients by several orders of magnitude over the uncorrected Landau-Zener values and remove the large gap between the latter and experimental results.
Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Haifa 32000, Israel.
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Dashevskaya
Institut für Physikalische Chemie, Universität Göttingen, Tammannstrasse 6, D-37077 Göttingen, Germany.
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Litvin
Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Haifa 32000, Israel.
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Nikitin
Max-Planck-Institut für Biophysikalische Chemie, Am Fassberg 11, D-37077 Göttingen, Germany.
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Troe
D001128:Argon / Q000737:chemistry*; D007700:Kinetics; D009569:Nitric Oxide / Q000737:chemistry*; D011336:Probability; D011789:Quantum Theory; D013696:Temperature; D014732:Vibration
D009569:Nitric Oxide; D001128:Argon