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Theoretical analysis of isotope effects on ozone formation in oxygen photochemistryIn situ measurements of stratospheric ozone and laboratory studies of ozone production in electric discharge through oxygen have shown previously that ozone containing heavy isotopes of oxygen (O-17, O-18) may be formed preferentially. In order to assess the relevance of thee latter experiment to the stratospheric measurements, detailed understanding of the effect of isotopic substitution on the O3 formation reaction O + O2 + M yields O3 + M and on the O atom exchange reaction O + O2 + O yields O2 + O is necessary. In this work, an estimate of the effect of isotopic substitution on the recombination rate is made by us of approximate dynamical theories and statistical mechanics. The results indicate the possibility of isotope effects on the O + O2 recombination rate of the order of several percent at stratospheric temperatures. In general, recombination reactions involving heavy (mass 49, 50) O3 formation are found to be slower than the reaction leading to normal (mass 48) O3 formation. The calculated isotope effects are sufficiently small that the uncertainties in the model input and the approximations in the dynamical theories will probably make the quantitative nature of these results subject to considerable uncertainty. This isotope effect should not be observable in the atmosphere given the precision of the current measurements but may be crucial in the understanding of the laboratory experiments, where observed enhancements are only of the order of several percent. Possible reasons for this discrepancy between the observed enhancement and predicted depletion are presented.
Document ID
19860061744
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Kaye, J. A.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Date Acquired
August 12, 2013
Publication Date
June 20, 1986
Publication Information
Publication: Journal of Geophysical Research
Volume: 91
ISSN: 0148-0227
Subject Category
Geophysics
Accession Number
86A46482
Distribution Limits
Public
Copyright
Other

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