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Dissociation of diatomic gasesThe Landau-Zener theory of reactive cross sections has been applied to diatomic molecules dissociating from a ladder of rotational and vibrational states. Although the preexponential factor of the Arrhenius rate expression is shown to be a complex function of the dimensionless activation energy, the average over all states in the ladder is well represented by a single factor that varies about as T exp (-n), where the coefficient n is the order of unity. This relation agrees very well with experimental data for dissociation of O2 and N2, for example. The results validate previous empirical assignment of a single preexponential factor in the Arrhenius expression and justify the extrapolation of the expression well beyond the range of data. The theory is then used to calculate the effect of vibrational nonequilibrium on dissociation rate. For Morse oscillators the results are about the same as for harmonic oscillators, and the dissociation from a ladder of equilibrium rotational and nonequilibrium vibrational states is close to an analytic approximation provided by Hammerling, Kivel, and Teare for harmonic oscillators all dissociating from the ground rotational state.
Document ID
19920030358
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Hansen, C. F.
(Oregon, University Eugene, United States)
Date Acquired
August 15, 2013
Publication Date
November 15, 1991
Publication Information
Publication: Journal of Chemical Physics
Volume: 95
ISSN: 0021-9606
Subject Category
Atomic And Molecular Physics
Accession Number
92A12982
Funding Number(s)
CONTRACT_GRANT: NAG1-1046
Distribution Limits
Public
Copyright
Other

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