Mechanisms of Charge Trapping at a Dielectric Surface: Resonance Stabilization and Dissociative Attachment

Abstract

A solid Kr film partially covered with ${\mathrm{O}}_2$ molecules is charged by a 0- to 10-eV electron beam. The electron energy dependence of the trapping cross section indicates that surface charging in the 0-2-eV range is due to stabilization via the ${}_{}{}^2{}_{}{}^{}\Pi _{\mathrm{g}}^{}{}_{}{}^{}{{\mathrm{O}}_2}^{-}$ resonance, whereas in the 4-10-eV region, it is due to ${\mathrm{O}}^{-}\left({}_{}{}^2{}_{}{}^{}P\right)$ formed by dissociation of the intermediate ${}_{}{}^2{}_{}{}^{}\Pi _{\mathrm{u}}^{}{}_{}{}^{}$ state of ${\mathrm{O}}_2^{-}$.