Thermal rate constants of the N₂+O→NO+N reaction using ab initio ³A″ and ³A′ potential energy surfaces

Theoretical determinations of the thermal rate constants and product energy distributions of the N₂+O→NO+N reaction, which plays a crucial role in hydrocarbon air combustion and high temperature air chemistry, are carried out using a quasiclassical trajectory method. An analytical fit of the lowest ³A′ potential energy surface of this reaction based on the CCI ab initio data is obtained. The trajectory study is done on this surface and an analytical ³A″ surface proposed by Gilibert et al. [J. Chem. Phys. 97, 5542 (1992)]. The thermal rate constants computed from 3000 to 20 000 K are in good agreement with the available experimental data. In addition, the dependence of the rate constant on the N₂ internal state is studied. It is found that a low vibrational excitation can reduce the rate constant of this reaction by a factor of 3. Also, we investigate the effect of the N₂ vibrational state on the product NO vibrational distribution, and it is found that at low N₂ vibrational states, the NO vibrational distribution is nearly Boltzmann. However, at N₂(v≳10), the product distribution is almost uniform at low energy levels.