Determination of NO (v=0–7) product distribution from the N(4S)+O2 reaction using two-photon ionization

Abstract

The product vibrational state distribution for the reaction N(⁴S)+O₂→NO(²Π,v)+O has been measured using saturated multiphoton ionization spectroscopy to determine NO electronic ground‐state distributions. The fraction of the reaction exothermicity appearing in product vibration is 〈 f _v〉=0.34; however, the even vibrational levels (v=0,2,4,6) are relatively overpopulated with respect to the odd vibrational levels (v=1,3,5). It is not possible to obtain a good linear‐surprisal fit to all the data, but the even and odd subsets fit quite well to individual surprisal plots. The results are compared with previous measurements, including a reanalysis of laser‐excited fluorescence data corrected for electronic transition moment and Franck–Condon factor variations. Collisional relaxation is observed at high O₂ pressures for NO levels v=4 through 7, and is fit with a phenomenological relaxation model.