Electron excitation of electronic states of the CO molecule

Abstract

The electron-impact excitation cross sections of the $A^{1}\ensuremath{\Pi}$, $E^{1}\ensuremath{\Pi}$, $B^{1}\ensuremath{\Sigma}^{+}$, $C^{1}\ensuremath{\Sigma}^{+}$, $D^{1}\ensuremath{\Delta}$, $a^{3}\ensuremath{\Pi}$, $c^{3}\ensuremath{\Pi}$, $b^{3}\ensuremath{\Sigma}^{+}$, $j^{3}\ensuremath{\Sigma}^{+}$, ${a}^{\ensuremath{'}}^{3}\ensuremath{\Sigma}^{+}$, and $d^{3}\ensuremath{\Delta}$ states of the CO molecule have been calculated for the incident electron energies over the range of threshold to 1000 eV for the singlet states and up to 100 eV for the triplet states by means of the Born approximation with Ochkur's and Rudge's modification for treating electron-exchange scattering. The wave functions of the various electronic states used in this calculation were determined by the self-consistent-field procedure with the Gaussian-type orbitals as basis functions. The calculated generalized oscillator strengths of the $A^{1}\ensuremath{\Pi}$, $E^{1}\ensuremath{\Pi}$, and $C^{1}\ensuremath{\Sigma}^{+}$ state are in reasonable agreement with the experimental values of Lassettre et al., but a larger discrepancy is found for the $B^{1}\ensuremath{\Sigma}^{+}$ state. The total cross sections calculated by this scheme show satisfactory agreement with experiment (30% at 300 eV) for the $A^{1}\ensuremath{\Pi}$ state and are generally within the range of uncertainty of the experimental data for $a^{3}\ensuremath{\Pi}$. For the $B^{1}\ensuremath{\Sigma}^{+}$ and $b^{3}\ensuremath{\Sigma}^{+}$ states the theoretical cross sections differ very significantly from the experimental data of Skubenich which, however, are in serious disagreement with measurements reported from two other laboratories.