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Science 23 September 1994:
Vol. 265. no. 5180, pp. 1831 - 1838
DOI: 10.1126/science.265.5180.1831
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Articles

The "Ozone Deficit" Problem: O2(X, v ge 26) + O(3P) from 226-nm Ozone Photodissociation

R. L. Miller 1, A. G. Suits 1, P. L. Houston 1, R. Toumi 2, J. A. Mack 3, and A. M. Wodtke 1

1 Department of Chemistry, Cornell University, Ithaca, NY, USA 14853-1301
2 Centre for Atmospheric Science, Department of Chemistry, Lensfield Road, Cambridge CB2 1EW, United Kingdom
3 Department of Chemistry, University of California, Santa Barbara, CA, USA 93106

Highly vibrationally excited O2(X3sgrg–, v ge 26) has been observed from the photodissociation of ozone (O3), and the quantum yield for this reaction has been determined for excitation at 226 nanometers. This observation may help to address the "ozone deficit" problem, or why the previously predicted stratospheric O3 concentration is less than that observed. Recent kinetic studies have suggested that O2(X3sgrg–, v ge 26) can react rapidly with O2 to form O3 + O and have led to speculation that, if produced in the photodissociation of O3, this species might be involved in resolving the discrepancy. The sequence O3 + hv rarr O2(X3sgrg–, v ge 26) + O; O2(X3sgrg–, v ge 26) + O2 rarr O3 + O (where hv is a photon) would be an autocatalytic mechanism for production of odd oxygen. A two-dimensional atmospheric model has been used to evaluate the importance of this new mechanism. The new mechanism can completely account for the tropical O3 deficit at an altitude of 43 kilometers, but it does not completely account for the deficit at higher altitudes. The mechanism also provides for isotopic fractionation and may contribute to an explanation for the anomalously high concentration of heavy O3 in the stratosphere.

Submitted on April 8, 1994
Accepted on August 8, 1994


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Enhanced Reactivity of Highly Vibrationally Excited Molecules on Metal Surfaces.
H. Hou, Y. Huang, S. J. Gulding, C. T. Rettner, D. J. Auerbach, and A. M. Wodtke (1999)
Science 284, 1647-1650
   Abstract »    Full Text »
Energetic Molecular Oxygen in the Atmosphere.
T. G. Slanger (1994)
Science 265, 1817-1818
   PDF »


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