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Application of unimolecular reaction rate theory for highly flexible transition states to the dissociation of CH2CO into CH2 and CO

Klippenstein, Stephen J. and Marcus, R. A. (1989) Application of unimolecular reaction rate theory for highly flexible transition states to the dissociation of CH2CO into CH2 and CO. Journal of Chemical Physics, 91 (4). pp. 2280-2292. ISSN 0021-9606. http://resolver.caltech.edu/CaltechAUTHORS:KLIjcp89

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Abstract

A previously described implementation of Rice–Ramsberger–Kassel–Marcus (RRKM) theory for unimolecular dissociation processes involving a highly flexible transition state is applied to the dissociation of CH2CO into CH2 and CO. Results of theoretical calculations for the energy and angular momentum resolved rate constants are presented. Using an added dynamical approximation, the product vibrational–rotational distributions are also calculated. The calculated rate constants are compared with the corresponding experimentally determined quantities where possible. Comparison is also made with phase space theory (PST). The RRKM-based calculations are in good agreement with both the experimentally determined rate constants of Zewail and co-workers and the experimentally determined photofragment excitation spectra of Moore and co-workers. The results on rates are in contrast to the corresponding results from PST calculations. The RRKM-based theory for the product vibrational–rotational distributions predicts a moderately greater probability for vibrational excitations than does PST (particularly for excess energies just above the threshold for excitation of a particular vibrational mode of the products). In other respects the RRKM-based predictions of the ro-vibrational product state distributions are quite similar to those of PST.


Item Type:Article
Additional Information:Copyright © 1989 American Institute of Physics. Received 21 October 1988; accepted 12 May 1989. It is a pleasure to acknowledge the support of this research by the National Science Foundation. The authors would like to thank A. Hoffmann, L.R. Khundkar, and A.H. Zewail for making the results of their picosecond spectroscopy experiments available to us prior to publication. S.J.K. also wishes to thank W.H. Green, Jr. and W. Nadler for helpful discussions. Arthur Amos Noyes Laboratory of Chemical Physics, Contribution No. 7851.
Subject Keywords:DISSOCIATION, CHEMICAL REACTION KINETICS, KETENES, METHYLENE RADICALS, CARBON MONOXIDE, VIBRATIONAL STATES, ROTATIONAL STATES, ENERGY−LEVEL DENSITY, MOLECULAR FRAGMENTS
Record Number:CaltechAUTHORS:KLIjcp89
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:KLIjcp89
Alternative URL:http://dx.doi.org/10.1063/1.457035
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:10291
Collection:CaltechAUTHORS
Deposited By: Archive Administrator
Deposited On:22 Apr 2008
Last Modified:26 Dec 2012 09:58

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