Vibrational Excitation of CO Fragments in Dissociative Attachment in CO2

Abstract

The dissociative attachment cross section for ${\mathrm{O}}^{-}$ from C${\mathrm{O}}_2$ in the neighborhood of 4.4 eV is examined with high resolution, and structure in this cross section is observed. We interpret this structure as an indication that vibrationally excited states of CO are produced in the reaction $e+{\mathrm{CO}}_2\to \mathrm{O}+\mathrm{CO}$. The magnitude of the cross section for the production of CO for individual states ($\nu =0\mathrm{}-3$) is estimated. The peak magnitudes of the dissociative attachment cross sections for production of CO in the vibrational states $\nu =0,1,2\mathrm{}$, and 3 are in the ratio of approximately 1:0.63:0.40:0.10. The threshold region for the dissociative attachment cross section in C${\mathrm{O}}_2$ is examined in the temperature range (200-300)° K, and it is found that this region can be described by a nonvertical onset and by the contribution of the bending mode to the attachment process.