Electronic excitation and dissociation of O2 and S2 by electron impact.

Abstract

The impact-parameter method is used to calculate integral cross sections for electronic excitation and dissociation of ${\mathrm{O}}_{2}$ and ${\mathrm{S}}_{2}$ by electron impact. For both molecules, excitations to bound and dissociative states are considered for transitions from the ground electronic state (X ${\mathrm{}}^{3}$${\ensuremath{\Sigma}}_{g}^{\mathrm{\ensuremath{-}}}$) to the two lowest states of $^{3}\mathrm{\ensuremath{\Sigma}}_{\mathrm{u}}^{\mathrm{\ensuremath{-}}}$ symmetry (labeled B and E for ${\mathrm{O}}_{2}$ and B and 2 for ${\mathrm{S}}_{2}$) and the lowest state of $^{3}\mathrm{\ensuremath{\Pi}}_{\mathrm{u}}$ symmetry. The dependence of the cross sections upon initial vibrational and rotational states is studied for low collision energies (threshold to 25 eV). For some transitions a change in initial vibrational state can have a significant effect upon the cross sections, but, in general, the effect of changing the initial rotational state is small.