Differential cross sections for dissociative attachment in CO

Abstract

An electron-impact spectrometer is described which, by means of a modification, is able to observe energy and angular distributions of ion fragments produced by molecular dissociation processes with a good precision and sensitivity. ${\mathrm{O}}^{\ensuremath{-}}$ ion formation through dissociative electron capture in CO has been studied. An analysis of the observed ${\mathrm{O}}^{\ensuremath{-}}$ differential cross sections using the theory of O'Malley and Taylor and two partial waves indicates that the two reactions leading to ${\mathrm{O}}^{\ensuremath{-}}$ both proceed through a $^{2}\ensuremath{\Pi}$ resonant state. Both resonances appear to have a ${\ensuremath{\sigma}}^{2}{\ensuremath{\pi}}^{3}{\ensuremath{\pi}}^{2}$ configuration by analogy with isoelectronic NO, and their parents would be the ${a}^{\ensuremath{'}}^{3}\ensuremath{\Sigma}^{+}$, for the process with a 9.62-eV threshold, and possibly the $d^{3}\ensuremath{\Delta}$ state, for the process with an onset at 10.88 eV.