Dissociative Attachment in CO and NO

Abstract

The electron energy dependences of the cross sections and of the ion kinetic energy distributions have been measured for ${\mathrm{O}}^{-}$ production from CO and NO. The present apparatus permits total collection measurements as well as kinetic energy analysis and mass identification of the ions produced. It is shown that in CO two reactions contribute to the single peak in the cross section, whereby carbon atoms are produced in their ground state and in their first excited state (${}_{}{}^1{}_{}{}^{}D$) respectively. The first reaction is predominant, and known from previous work to have a peak cross section of 2.0 × ${10}^{-19\mathrm{}}$ ${\mathrm{cm}}^2$. Normalized to this, the second reaction is shown to have a peak cross section of 9.5 × ${10}^{-21\mathrm{}}$ ${\mathrm{cm}}^2$. In NO it is shown that ${\mathrm{O}}^{-}$ production proceeds exclusively through the reaction $e+\mathrm{NO}\to {\mathrm{O}}^{-}+{\mathrm{N}}^{*}$ where $\mathrm{N}*$ is the first excited state (${}_{}{}^2{}_{}{}^{}D$). No ${\mathrm{O}}^{-}$ ions are observed corresponding to the formation of ground state N. Nor is there any evidence for the production of the second excited state of nitrogen, $\mathrm{N}\left({}_{}{}^2{}_{}{}^{}P\right)$, postulated by Dorman to account for the structure in the attachment cross section.