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Evidence for o-atom exchange in the O(1D) + N2O reaction as the source of mass-independent isotopic fractionation in atmospheric N2O

Muller, Richard P.

Recent experiments have shown that in the oxygen isotopic exchange reaction for O({sup 1}D) + CO{sub 2} the elastic channel is approximately 50% that of the inelastic channel [Perri et al., 2003]. We propose an analogous oxygen atom exchange reaction for the isoelectronic O({sup 1}D) + N{sub 2}O system to explain the mass-independent isotopic fractionation (MIF) in atmospheric N{sub 2}O. We apply quantum chemical methods to compute the energetics of the potential energy surfaces on which the O({sup 1}D) + N{sub 2}O reaction occurs. Preliminary modeling results indicate that oxygen isotopic exchange via O({sup 1}D) + N{sub 2}O can account for the MIF oxygen anomaly if the oxygen atom isotopic exchange rate is 30-50% that of the total rate for the reactive channels.