Dynamics of the N(4S u)+NO(X 2Π)→N2(X 1Σ+g)+O(3P g) atmospheric reaction on the 3A″ ground potential energy surface. II. The effect of reagent translational, vibrational, and rotational energies

Abstract

The effect of translational vibrational, and rotational energies on the dynamics of the N(⁴S_u)+NO(X ²Π)→N₂(X ¹Σ_g⁺)+O(³P_g) reaction has been examined using a Sorbie–Murrell analytical fitting of a grid of ab initio configuration interaction (CI) points for the ³A‘ ground potential energy surface reported by the authors in a previous work. Translational energy is shown to increase total reaction cross section for all the initial rovibrational states of reactants considered. The reaction mode analysis points towards a direct mechanism and a strong influence of the shape of the potential energy surface on the reactivity, especially at low relative collision energies. Vibrational excitation of the NO reactant molecule changes the total reaction cross section values moderately, while increasing the initial rotational states of NO at low fixed relative collision energies decreases the reaction cross section sharply, eventually becoming zero for the highest J values explored. By comparing with model calculations on the same surface involving extreme H+HL and L+LH mass combinations, the microscopic reaction mechanism is shown to imply product molecules being created with rotational angular momentum (J ’) oriented preferentially antiparallel with respect to their orbital angular momentum (l ’) at low relative energies, with loss of orientation for higher relative energies. Thus, the surface used indicates a strong vector correlation between l ’ and J ’ and also an important influence in equipartitioning total angular momentum between the rotational and orbital angular momenta of products. Comparison with unfortunately scarce experimental data (e.g., fraction of vibrational energy in products and rate constants) shows a very good agreement.