Cross sections for the rotationally inelastic scattering of Ne + N2: application of the exponential semi-classical distorted wave approximation

Abstract

Exact quantum-mechanical close-coupling and approximate calculations are presented for Ne + N₂ collisions using a model potential. The approximate calculations were performed using an exponential semi-classical distorted wave approximation (ESCDW) which is outlined in the paper. The ESCDW approximation involves the evaluation of the same integrals as the standard distorted wave approximation. The former method, however, in contrast to the latter, yields a unitary S matrix and therefore conserves particle flux. The exponentiation process is shown to lead to dramatic improvements in the calculated cross sections for the present system. Cross sections evaluated using the ESCDW approximation compare very well with exact ones over the entire range of thermally accessible energies. Total and differential rotationally inelastic cross sections are presented and their variation with energy is examined. The dependence of the cross sections on the number of coupled channels included in the calculations is also investigated and a sufficient number of channels are included to ensure convergence.