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Published July 1987 | public
Journal Article

The effect of pressure and excitation energy on the isotopic fractionation in the formation of ozone by discharge of O_2

Abstract

Studies were made to determine the effect of the variation of the isotopic composition of initial O_2, discharge energy increase and the pressure on the isotopic composition of the O_3 produced from molecular oxygen. An RF generator with several frequency modes, the highest one at 3 MHz was used for the excitation of O_2 molecules. The pressure of the initial O_2 gas was varied from 2 to 15 cm Hg. The isotopomeric patterns produced by this generator are moderately different from those by an RF generator of lower frequencies. We used oxygen gases of three different isotopic compositions. The slope of δ_233/δ_234 varied with composition and pressure continuously between 1.19 to -1/2, passing values of ±∞. The significance of this is that ^(17)O and ^(18)O enrichments in this reaction can take place independent of one another. All data are compatible with a model based on the anharmonic predissociation of vibrationally hot O_3. The theory has two parameters p and q which depend on the distribution of vibrational states of ozone as affected by the symmetry. Several investigations are suggested by our results, including the possible explanation for the oxygen isotope anomalies found in meteorites.

Additional Information

© 1987 Pergamon Journals Ltd. Received February 4, 1986; accepted in revised form April 24, 1987. The authors are indebted to V. Nenow for his help during the series of technical developments and S. K. Shin for his discussion on molecular chemistry. They also thank the following people for their support through scientific discussion and encouragement: G. J. Wasserburg, I. Anders. J. H. Chen. J. Coulson, H. Kang, J. S Kim, Y. B. Kim, A. Kuppermann, H. Kwon, M. Murrell, D. Papanastassiou, C. Patterson. R. S. Rajan, I. Robert and J. K. Yang. This research was supported by NASA NGL 05-002-190. We wish to acknowledge some financial support by Korea Science and Engineering Foundation to one of J. Yang which assisted us to complete this work. Editorial handling: K. Marti

Additional details

Created:
August 19, 2023
Modified:
October 25, 2023