A STUDY OF THE FORMATION OF N2O IN THE REACTION OF NO3(A(2)E') WITH N2

The rate of formation of N2O via the thermochemically favourable reaction of NO3(A2E') with N2, which would represent an additional source of stratospheric N2O and therefore NO(x), has been investigated. Mixtures of NO2 + O3 in synthetic air were photolysed at 662 nm. No evidence was found for the production of N2O via this pathway, the upper limit for the quantum yield of nitrous oxide formation being phi(N2O) less-than-or-equal-to 0.6%. However, a dark conversion of NO(x) to N2O was observed and is attributed tentatively to a heterogeneous reaction on the wall of the reaction vessel. This process, although most likely to be insignificant in the atmosphere, needs to be taken into consideration in laboratory investigations or field studies of N2O emission or deposition.