Direct detection of N(4S) 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(2p23s 4P1/2 - 2p3 4S3/2) transition has been generated by two-photon resonant four-wave sum frequency mixing in Hg vapor. The quantum yield value for N(4S) formation in the N2O photolysis at 193 nm has been determined to be 2.1 (¿0.9) ¿ 10-3. The N(4S) detection technique, which is developed in this study, is very sensitive, and the minimum detection limit is estimated to be 2 ¿ 109 atoms cm-3. Impact of the photolytic N(4S) and NO(X2Π) 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(4S) + 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 O3 concentration throughout the stratosphere.