Resonances in the electronic excitation of molecular hydrogen

Abstract

Ab initio R-matrix scattering calculations are presented for electron-${\mathrm{H}}_2$ collisions for energies up to 30 eV. Excitation from the ground state, ${\mathit{X}}^1$ ${\mathrm{\Sigma }}_{\mathit{g}}^{+}$, to five accurately represented, low-lying electronic states, ${\mathit{b}}^3$ ${\mathrm{\Sigma }}_{\mathit{u}}^{+}$, ${\mathit{a}}^3$ ${\mathrm{\Sigma }}_{\mathit{g}}^{+}$, ${\mathit{B}}^1$ ${\mathrm{\Sigma }}_{\mathit{u}}^{+}$, ${\mathit{c}}^3$ ${\mathrm{\Pi }}_{\mathit{u}}$, and ${\mathit{C}}^1$ ${\mathrm{\Pi }}_{\mathit{u}}$, is explicitly considered. An attempt is made to rationalize the wealth of experimental data. Resonance structures similar to those assigned experimentally to the a and c series are found as well as a number of other resonancelike features.