Isotope Effects in Collisional VT Relaxation of Molecular Hydrogen
A simple exponential-potential model of molecular collisions leads to a twoparameter analytic expression for rates of collisionally induced vibrationaltranslation (VT) energy exchange that has been shown to be accurate over variations of orders of magnitude as a function of temperature in a variety of systems. This includes excellent agreement with reported experimental and theoretical results for the fundamental self-relaxation rate of molecular hydrogen H2(v = 1) + H2 → H2(v = 0) + H2. The analytic rate successfully follows the five-orders-of-magnitude change in experimental values for the temperature range 50-2000 K. This approach is now applied to isotope effects in the vibrational relaxation rates of excited HD and D2 in collision with H2: HD(v = 1)+H2 → HD(v = 0)+H2 and D2(v = 1)+H2 → D2(v = 0)+H2. The simplicity of the analytic expression for the thermal rate lends itself to convenient application in modeling the evolving vibrational populations of molecular hydrogen in shocked astrophysical environments.
R. J. Bieniek, "Isotope Effects in Collisional VT Relaxation of Molecular Hydrogen," Proceedings of the 2006 NASA Laboratory Astrophysics Workshop, National Aeronautics and Space Administration (NASA), Feb 2006.
University of Nevada, Las Vegas
Keywords and Phrases
Vibrational-Translation (VT) Energy; Collisions (Nuclear physics); Hydrogen; Isotopes
Article - Conference proceedings
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