An Explanation for Symmetry-Induced Isotopic Fractionation in
Ozone
Gregory I. Gellene
Application of a theory of nuclear symmetry-based reaction
restrictions to the O2 + O
O3 reaction
provides a potential explanation for the symmetry-induced isotopic
enrichment observed for laboratory and atmospherically produced
O3. Within this theory, the rate of formation of
O3 from collisions of O and isotopically homonuclear O2 depends on whether the O2 molecule is in an
f (allowed) or an e (restricted) parity
label state. The restriction can be relaxed by various potential energy
surface coupling terms, and the assumption that approximately 78 percent of the restricted O2(e) levels produce O3 with the same efficiency as the allowed
O2(f) levels can account for
laboratory-observed isotopic fractionation. In particular, the theory
explains the special enhanced formation of the completely asymmetric
isotopomer 16O17O18O.
Department of Chemistry and Biochemistry, Texas Tech University,
Lubbock, TX 79409, USA.