Stereodynamics of dissociative electron attachment to CO${}_2$ is investigated using O${}^{-}$ anion velocity imaging experiments. Here ${}^2{\Pi }_g$ as a Feshbach resonant state of CO${}_2$${}^{-}$ is confirmed to play a role in the dissociation CO${}_2$${}^{-}$ → CO(${}^1{\Sigma }^{+}$) + O${}^{-}$(${}^{2}P$) around 8.0 eV. At the lower energy, 7.7 eV, two split states of ${}^2{\Pi }_g$ due to the Renner-Teller effect are found to couple with the dissociation path; while above this energy, at 8.2 and 8.7 eV, the coupling between the dissociation and the C-O bond stretching becomes predominant. The evolutions of the potential energy surface around this Feshbach resonant state result in the dramatically different angular distributions of the O${}^{-}$ momentum.

• Received 30 October 2011

DOI:https://doi.org/10.1103/PhysRevA.85.052709