Electron-impact study of the NH radical using theR-matrix method

Abstract

We have employed the R-matrix method to compute elastic (integrated and differential), momentum-transfer, excitation, and ionization cross sections for electron impact on the NH radical. The target states are represented by including correlations via a configuration interaction technique. The results of the static exchange, correlated one-state configuration interaction, and 19-state close-coupling approximation are presented. We have detected a stable anionic bound state {sup 2{Pi}} of NH{sup -} having the configuration 1{sigma}{sup 2}2{sigma}{sup 2}3{sigma}{sup 2}1{pi}{sup 3}. The data of the momentum-transfer cross section, generated from the differential cross section, is used to compute effective collision frequencies over a wide electron temperature range (200-30 000 K). The ionization cross sections are calculated in the binary-encounter Bethe model in which Hartree-Fock molecular orbitals at self-consistent levels are used to calculate kinetic and binding energies of the occupied molecular orbitals. We have included up to the g partial wave (l=4) in the scattering calculations. For this dipolar molecule we have used a Born-closure top-up procedure to account for the higher partial waves for the convergence of the cross section.