The role of symmetry in the mass independent isotope effect in ozone.

Understanding the internal distribution of "anomalous" isotope enrichments has important implications for validating theoretical postulates on the origin of these enrichments in molecules such as ozone and for understanding the transfer of these enrichments to other compounds in the atmosphere via mass transfer. Here, we present an approach, using the reaction NO(2)(-) + O(3), for assessing the internal distribution of the Delta(17)O anomaly and the delta(18)O enrichment in ozone produced by electric discharge. The Delta(17)O results strongly support the symmetry mechanism for generating mass independent fractionations, and the delta(18)O results are consistent with published data. Positional Delta(17)O and delta(18)O enrichments in ozone can now be more effectively used in photochemical models that use mass balance oxygen atom transfer mechanisms to infer atmospheric oxidation chemistry.