QUASI-CLASSICAL TRAJECTORY STUDY OF THE N(S-4(U))+O-2(X 3-SIGMA-G-)-]NO(X 2-PI)+O(P-3(G)) ATMOSPHERIC REACTION ON THE (2)A' GROUND POTENTIAL-ENERGY SURFACE EMPLOYING AN ANALYTICAL SORBIE-MURRELL POTENTIAL

The reaction between ground state nitrogen atoms and oxygen molecules plays an important role in the chemistry of the upper atmosphere as a source of infrared chemiluminescence and also as a participant in the auroral mechanism. Even though the- is considerable experimental stock concerning rate constants over a wide range of temperatures and also on the vibrational distribution of products, as well as theoretical information about the potential energy surfaces of this system, no extensive work is available on its dynamical features. The present paper is concerned with the construction of an analytical Sorbie-Murrell surface for the lowest 2A' surface correlating reactants and products in their ground electronic states, based upon the reproduction of a grid of ab initio CI points and a preliminary dynamics on that surface. The analytical potential energy surface fits the corrected ab initio CI barrier of 7.6 kcal/mol, in agreement with the experimental estimates, exhibiting also a repulsive behaviour of the NOO bending at the saddle point configuration. Quasiclassical trajectories lead on the whole to a rather good reproduction of the different experimental properties measured. The calculated vibrational distribution resulting from the present QCT calculations does not however fully agree with any of the existing experimental, mutually conflicting, measurements.