Excitation of Vibrational and Electronic Levels inO2by Electron Impact

Low-energy inelastic collisions between electrons and oxygen molecules are studied using the trapped-electron method. Peaks in the trapped-electron current are interpreted as vibrational excitation of the oxygen molecule to the states $v=1\mathrm{}$ to $v=8\mathrm{}$. Two of these peaks can be attributed in part to the excitation of the ${}_{}{}^1{}_{}{}^{}\Delta g$ and ${{}_{}{}^1{}_{}{}^{}\Sigma _g^{}{}_{}{}^{}}^{+}$ states. Approximate cross sections at 0.16 eV above threshold are less than 3×${10}^{-20\mathrm{}}$ and 6×${10}^{-21\mathrm{}}$ ${\mathrm{cm}}^2$ for the ${}_{}{}^1{}_{}{}^{}\Delta g$ and ${{}_{}{}^1{}_{}{}^{}\Sigma _g^{}{}_{}{}^{}}^{+}$ states, respectively. For electronic states above 5 eV, the cross sections at 0.16 eV above threshold are of the order of ${10}^{-18\mathrm{}}$ ${\mathrm{cm}}^2$.