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Author Lombardi, A. ♦ Faginas-Lago, N. ♦ Pacifici, L. ♦ Grossi, G.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword ATOMIC AND MOLECULAR PHYSICS ♦ ACCURACY ♦ CARBON DIOXIDE ♦ COLLISIONS ♦ CROSS SECTIONS ♦ DEGREES OF FREEDOM ♦ ENERGY BALANCE ♦ ENERGY TRANSFER ♦ HYPERSONIC FLOW ♦ INTERACTIONS ♦ INTERMOLECULAR FORCES ♦ MIXTURES ♦ MOLECULES ♦ PLANETARY ATMOSPHERES ♦ PROBABILITY ♦ SIMULATION
Abstract Carbon dioxide molecules can store and release tens of kcal/mol upon collisions, and such an energy transfer strongly influences the energy disposal and the chemical processes in gases under the extreme conditions typical of plasmas and hypersonic flows. Moreover, the energy transfer involving CO{sub 2} characterizes the global dynamics of the Earth-atmosphere system and the energy balance of other planetary atmospheres. Contemporary developments in kinetic modeling of gaseous mixtures are connected to progress in the description of the energy transfer, and, in particular, the attempts to include non-equilibrium effects require to consider state-specific energy exchanges. A systematic study of the state-to-state vibrational energy transfer in CO{sub 2} + CO{sub 2} collisions is the focus of the present work, aided by a theoretical and computational tool based on quasiclassical trajectory simulations and an accurate full-dimension model of the intermolecular interactions. In this model, the accuracy of the description of the intermolecular forces (that determine the probability of energy transfer in molecular collisions) is enhanced by explicit account of the specific effects of the distortion of the CO{sub 2} structure due to vibrations. Results show that these effects are important for the energy transfer probabilities. Moreover, the role of rotational and vibrational degrees of freedom is found to be dominant in the energy exchange, while the average contribution of translations, under the temperature and energy conditions considered, is negligible. Remarkable is the fact that the intramolecular energy transfer only involves stretching and bending, unless one of the colliding molecules has an initial symmetric stretching quantum number greater than a threshold value estimated to be equal to 7.
ISSN 00219606
Educational Use Research
Learning Resource Type Article
Publisher Date 2015-07-21
Publisher Place United States
Journal Journal of Chemical Physics
Volume Number 143
Issue Number 3


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