Formation of nitrous oxide in the reaction of O(1D2) atoms with nitrogen

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Abstract
The quantum yields of N2O (φN2O) formed in the reaction of O(1D2) atoms with N2 have been determined in the gas phase at 23°C and at pressures between 25 and 115 atm and, for comparison, in liquid phase at cryogenic temperatures. Extrapolation of the gas phase results indicates for φN2O at 1 atm the very low value of 3×10−7, which precludes direct observation of N2O formation at 1 atm in laboratory experiments by the currently employed analytical techniques. With increasing pressure φN2O increases but does not show the simple dependence on [N2] predicted by the generally used mechanism based on the ’’strong collision’’ assumption. The results show instead a linear dependence of 1/φ1/2N2O on 1/[N2], which can be rationalized in terms of two alternative mechanisms. Although both mechanisms invoke a two stage deactivation of the energy rich initial adduct (N2O*), they differ in some important respects. The effects of additions of O2 and Ar have been also studied and can be explained well by the same two mechanisms but do not differentiate between them within the range of experimental conditions employed.