Remeasurement of atomic nitrogen(2P) + oxygen reaction rate using multiphoton ionization detection of nitrogen atoms

The authors have observed photoionization signals in a flowing afterglow reactor arising from the (2 + 1) photoionization of N(/sup 2/P) and N(/sup 2/D), resonantly enhanced by the two-photon transitions N(3p /sup 2/P/sup 0//sub J/) reverse arrow N(2p/sup 3/ /sup 2/P/sup 0//sub J/) and N(3p /sup 2/S/sup 0//sub 1/2/) reverse arrow N(2p/sup 3/ /sup 2/D/sup 0//sub J/), respectively. A diffusion-limited lifetime of 530 ..mu..s at 0.22 Torr was observed for N(/sup 2/P), indicating wall quenching with unit efficiency. Measurement of N(/sup 2/P) quenching by O/sub 2/ yielded a rate coefficient of (1.8 =/- 0.2) x 10/sup -12/ cm/sup 3/ s/sup -1/, which is significantly less than values previously obtained by using vacuum-UV resonance detection of the metastable nitrogen.