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On collisional energy transfer in recombination and dissociation reactions: A Wiener–Hopf problem and the effect of a near elastic peak

Zhu, Zhaoyan and Marcus, R. A. (2008) On collisional energy transfer in recombination and dissociation reactions: A Wiener–Hopf problem and the effect of a near elastic peak. Journal of Chemical Physics, 129 (21). Art. No. 214106. ISSN 0021-9606.

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The effect of the large impact parameter near-elastic peak of collisional energy transfer for unimolecular dissociation/bimolecular recombination reactions is studied. To this end, the conventional single exponential model, a biexponential model that fits the literature classical trajectory data better, a model with a singularity at zero energy transfer, and the most realistic model, a model with a near-singularity, are fitted to the trajectory data in the literature. The typical effect of the energy transfer on the recombination rate constant is maximal at low pressures and this region is the one studied here. The distribution function for the limiting dissociation rate constant k0 at low pressures is shown to obey a Wiener–Hopf integral equation and is solved analytically for the first two models and perturbatively for the other two. For the single exponential model, this method yields the trial solution of Troe. The results are applied to the dissociation of O3 in the presence of argon, for which classical mechanical trajectory data are available. The k0's for various models are calculated and compared, the value for the near-singularity model being about ten times larger than that for the first two models. This trend reflects the contribution to the cross section from collisions with larger impact parameter. In the present study of the near-singularity model, it is found that k0 is not sensitive to reasonable values for the lower bound. Energy transfer values <ΔE>'s are also calculated and compared and can be similarly understood. However, unlike the k0 values, they are sensitive to the lower bound, and so any comparison of a classical trajectory analysis for <ΔE>'s with the kinetic experimental data needs particular care.

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Marcus, R. A.0000-0001-6547-1469
Additional Information:© 2008 American Institute of Physics. Received 12 June 2008; accepted 22 October 2008; published 2 December 2008. It is a pleasure to acknowledge the support of this research by the National Science Foundation and to thank Professor Jau Tang for a helpful discussion and Professor Reinhard Schinke and Dr. Mikhail V. Ivanov for providing their detailed classical trajectory data.
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National Science FoundationUNSPECIFIED
Subject Keywords:association, dissociation, ozone, reaction kinetics theory, reaction rate constants
Issue or Number:21
Record Number:CaltechAUTHORS:ZHUjcp08
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:12493
Deposited By: Archive Administrator
Deposited On:11 Dec 2008 06:24
Last Modified:22 Nov 2019 09:58

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