The paper addresses the ahalysis, validation, and application of analytic, nonperturbative, semiclassical vibration-translation (V-T) and vibration-vibrationtranslation (V-V-T) rate models f o r atom-diatom and diatom-diatom vibrational molecular energy t r a n s f e r collisions. These "forced harmonic oscillator" (FHO) rate models are corrected and validated by comparison with recent experiments, and with threedimensional semiclassical trajectory calculations f o r N -N 0 -0 and N2-02. which are considered t o be the most reliable theoretical d a t a available. A remarkably good overall agreement i s shown, f o r both the temperature and quantum number dependence of single-quantum and double-quantum V-V-T transitions in the temperature range 2005T58000 K and f o r vibrational quantum numbers 0 9~5 4 0 . I t is demonstrated t h a t the multi-quantum. vibrational energy t r a n s f e r processes occur via a sequential FHO mechanism, as a series 2 2' 2 2'' L e c t u r e r , Dept. of Mechanical Engineering, OSU, Member AIAA 'Associate Research Scientist, Princeton University, Senior Member AIAA 3Professor, Dept. of Mechanical Engineering, OSU, Associate Fellow AIAA 4President, CTSA, Inc., Fellow AIAA Copyright@, 1995 by I.V. Adamovich, '3.0. Macheret, J.W. Rich, and C.E. Treanor Published by t h e American Institute of Aeronautics and Astronautics, Inc. with permission J -I Downloaded by UNIVERSITY OF NEW SOUTH WALES on August 2, 2015 | http://arc.aiaa.org | of virtual single-quantum steps during one collision.An important exception, asymmetric multi-quantum V-V exchange at low temperatures, t h a t occurs via a direct first-order mechanism, is discussed. Analytic thermally averaged FHO V-T and V-V rates are suggested. The FHO model gives new insight into vibrational kinetics and may be easily incorporated into kinetic modeling calculations under conditions when f i r s torder theories are not applicable. 1. I n t r o d u c t i o n Vibrational energy transfer in collisions of diatomic molecules plays a fundamental role in molecular lasers, gas discharges. plasma chemical reactors, highenthalpy gas dynamic flows, and in upper atmosphere chemistry. In these environments, i t creates and maintains strongly nonequilibrium molecular vibrational energy distributions (VDF), which induce nonequilibrium chemical reactions, electronic excitation, dissociation and ionization of diatomics (e.g. see [l-411. The rates of these high energy threshold processes a r e determined by the populations of the high vibrational levels of molecules. These populations are often controlled by vibrationtranslation (V-T) processes,and vibration-vibration-translation (V-V-TI processes, I /involving highly vibrationally excited molecules. In Eqs. (1,2) AB, CD and M represent diatomic molecules and an atom, respectively, and i i f l and f 2 are vibrational quantum numbers. 1' 2' There exists a n extensive literature on the experimental and theoretical study of V-T and V-V-T energy transfer (e.g. see [5-101 and references therein). However, experim...
