Kinetics of the reaction between atomic nitrogen and molecular oxygen in the ground (3∑-g) and first excited (1∆g) states

Abstract Rate constants for the reaction N + O2(1∆g) →k1 NO + O (1) have been measured at four temperatures, and fitted to an Arrhenius expression, k1 = A exp ( ─Ea/RT). The results indicate that A ≤ 2 x 10-14 molecule-1 cm3 s-1 and 1.2 kcal (5.0 kJ ) mol-1: at room temperature (300 K ), k1 = 2.7 ± 1.0 x 10-15 molecule-1 cm3 s-1. Reaction (1) cannot, therefore, proceed fast enough at 200 K for it to be an important source of nitric oxide in the atmospheric D-region. The rate constant for the reaction N + O2 (3∑─g) → k2 NO + O (2) has been measured at 302 K to be 1.08 ± 0.10 x 10-16 molecule-1 cm3 s-1. This value, taken together with the data of earlier workers, suggests that k2 = 1.5 x 10-11 exp (—7.1/RT) molecule-1 cm2 s-1. A possible explanation for the difference in pre-exponential factors for reactions (1) and (2) is presented.