Molecular Dynamics in Dissociative Electron Attachment to CO probed by Velocity Slice Imaging

Kinetic energy and angular distributions of O$^-$ ions formed by dissociative electron attachment to CO molecule have been studied for 9, 9.5, 10, 10.5, 11, 11.5 eV incident electron energies around the resonance using time sliced velocity map imaging spectrometer. Detailed observations clearly show two separate DEA reactions lead to the formation of O$^{-}$ ions in the ground $^{2}P$ state along with the neutral C atoms in ground $^{3}P$ state and first excited $^{1}D$ state, respectively. Within the axial recoil approximation and involving four partial waves, our angular distribution results clearly indicate that the two reactions leading to O$^{-}$ formation proceed through the distinct resonant state(s). For the first process, more than one intermediate states are involved. Whereas, for the second process, only one state is involved. The observed forward-backward asymmetry is explained due to the interference between the different partial waves that are involved in the processes.