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Ion-pair dissociation dynamics in electron collision with carbon dioxide probed by velocity slice imaging

Ion-pair dissociation (IPD) to gas phase carbon dioxide molecule has been studied using time of flight (TOF) based mass spectroscopy in combination with the highly differential velocity slice imaging (VSI) technique. The appearance energy of the fragmented anion provides the experimental threshold energy value for ion-pair production. The kinetic energy (KE) distributions and angular distributions (AD) of the fragment anion dispense the detailed insight into the IPD dynamics. The KE distribution clearly reveals that the IPD dynamics may be due to the direct access to the ion-pair states. However, indirect mechanism can't be ruled out at higher incident electron energies. The angular distribution data unambiguously identified the involvement of the ion-pair state associated with Sigma symmetry and a minor contribution from Pi symmetric states. Computational calculations using density functional theory (DFT) strongly support the experimental observations.