Oscillator strength and electron-impact excitation of the Schumann-Runge continuum of the oxygen molecule

By using the method of multiconfiguration self-consistent field, the electronic wave functions for the X³Σg^- and B³Σᵤ^- states of O₂ are determined for twelve values of internuclear distances. From the appropriate electronic-vibrational functions, the oscillator strengths for the X³Σg^-→B³Σᵤ^- absorption (Schumann-Runge) continuum are calculated over the energy range of 7-9.5 eV. The results are in good agreement with experiments except at the high-energy edge (above 9 eV) which corresponds to the very steeply varying part of the potential curve. A calculation of the electron-impact excitation cross sections for the B³Σᵤ^- state with the Born-Ochkur approximation is also reported for incident electron energy up to 1000 eV.