Differential cross sections for rovibrational(v′=0→1,2,3,4)excitation of the electronic ground state ofO2by electron impact

Abstract

We have measured absolute differential cross sections (DCSs) for rovibrational excitation $(\stackrel{\ensuremath{\rightarrow}}{0}1,2,3,4)$ of the $\ensuremath{\chi}{}^{3}{\ensuremath{\Sigma}}_{g}^{\ensuremath{-}}$ electronic ground state of ${\mathrm{O}}_{2}.$ The scattered electron angular range was 10\ifmmode^\circ\else\textdegree\fi{}--90\ifmmode^\circ\else\textdegree\fi{}, while the cross sections were measured at ten specific energies in the 5--20 eV incident beam energy range. This energy regime encompasses the region where the ${}^{4}{\ensuremath{\Sigma}}_{u}^{\ensuremath{-}}$ and ${}^{2}{\ensuremath{\Sigma}}_{u}^{\ensuremath{-}}$ resonances of ${\mathrm{O}}_{2}^{\mathrm{\ensuremath{-}}}$ are known to significantly enhance the vibrational excitation process. The present data are found to be in generally good agreement with the more limited recent measurements of Allan [J. Phys. B 28, 5163 (1995)] and the earlier results of Wong et al. [Phys. Rev. Lett. 31, 969 (1973)]. Agreement with the data of Shyn and Sweeney [Phys. Rev. A 48, 1214 (1993)], however, was found to be only fair. Comparison of the present DCS with an available Born-closure Schwinger variational method calculation result is also made.