A quasiclassical trajectory study of the effect of the initial rovibrational level and relative translational energy of reactants on the dynamics of the N(4Su) + O2(X 3∑−g) → NO(X 2Π) + O(3Pg) atmospheric reaction on the 2A′ ground potential energy surface

Abstract

The effect of translational, vibrational and rotational energy on the dynamics of the N(4Su) + O2(X 3∑−g) → NO(X 2Π) + O(3Pg) reaction has been investigated using a Sorbie-Murrell analytical fitting of a grid of ab initio CI points for the 2A′ ground potential energy surface reported by the authors in a previous work, by means of a quasiclassical trajectory study. Translational energy is shown to increase total reactive cross section for all initial rovibrational levels of reactants considered. Trajectories are found to proceed mainly through a direct mechanism, even though a minority of them exhibit a behaviour implying insertion of the N atom between both O atoms when the OO distance is long enough. This type of trajectory does not however influence the overall dynamical properties of the system. Vibrational excitation of reactants does not greatly influence the reactive cross section values even at low relative translational energies near threshold. On the other hand, rotational excitation of reactants causes the reaction cross section to increase slightly at the lowest relative energy value explored, while showing very little or almost no variation for higher relative translational energies. Comparison with experimental data shows a good agreement regarding the fraction of energy going to product vibration, although the shape of the vibrational distribution is not so well reproduced.