Quantum yield for N(4S) production in the ultraviolet photolysis of N2O -: art. no. 4668

[1] Direct detection of N(S-4) atom formation in the 193 nm photolysis of N2O by a technique of vacuum ultraviolet (vuv) laser-induced fluorescence spectroscopy has been reported. Tunable vuv laser radiation around 120.071 nm that is resonant to the one-photon N(2p(2)3s P-4(1/2) - 2p(3) S-4(3/2)) transition has been generated by two-photon resonant four-wave sum frequency mixing in Hg vapor. The quantum yield value for N(S-4) formation in the N2O photolysis at 193 nm has been determined to be 2.1 (+/-0.9) x 10(-3). The N(S-4) detection technique, which is developed in this study, is very sensitive, and the minimum detection limit is estimated to be 2 x 10(9) atoms cm(-3). Impact of the photolytic N(S-4) and NO(X(2)Pi) production from N2O photolysis on stratospheric chemistry has been explored using a one-dimensional photochemical model, while the fragmentation was not considered in former model calculations. When the N(S-4) + NO dissociation channel is considered in the photochemical model, an enhancement of the NOx production rate (up to 3%) is observed, which is followed by a decrease of the steady state O-3 concentration throughout the stratosphere.