Electron-impact study of S3 using the R-matrix method

We have carried out a comprehensive study of electron impact on the open-chain S-3 isomer by using the R-matrix method. Elastic (integrated and differential), momentum-transfer, excitation, and ionization cross sections, along with effective collision frequency over a wide electron temperature range (500-30 000 K) have been presented. The target states are represented by including correlations via a configuration interaction technique. The results of the static-exchange, correlated 1-state, and 24-state close-coupling approximations are presented. Our study has detected a shape resonance, six core-excited shape resonances, and one Feshbach resonance in the 24-state model. We detect a stable bound state of S-3(-) of B-2(1) symmetry having a configuration... 11a(1)(2),... 3b(1)(2)4b(1),... 2b(2)(2),... 2a(2)(2), with a vertical electronic affinity value of 2.15 eV, and a ionization potential value of 9.77 eV, which are in good agreement with the experimental values of 2.093 +/- 0.025 and 9.68 +/- 0.03 eV, respectively. The ionization cross sections are calculated using the binary-encounter-Bethe model in which Hartree-Fock molecular orbitals at a self-consistent level are used to calculate kinetic and binding energies of the occupied molecular orbitals. We have used partial waves up to l = 4 to represent continuum electron in our R-matrix method. A Born top-up procedure is invoked to account for the contribution of partial waves higher than l = 4 to obtain converged cross sections.