Dissociative electron attachment to molecules in vibrationally excited states is associated with lower threshold energies and higher cross sections than for cold targets. To date, fewer studies have been performed for polyatomic molecules than for diatomic molecules, due to the experimental challenges and theoretical difficulties in describing the complicated dynamics. Here we report an observation of the dissociative electron attachment to $\mathrm{C}{\mathrm{O}}_2$ in the vibrationally excited states, where the vibrationally excited $\mathrm{C}{\mathrm{O}}_2$ targets are prepared by the electron-impact excitation at energies close to the ${}^2{\mathrm{\Pi }}_u$ resonant state of $\mathrm{C}{{\mathrm{O}}_2}^{-}$. The high-resolution anion momentum images of the ${\mathrm{O}}^{-}$ yield indicate that the rovibrational state distributions of the coproduct CO are dependent on the vibrationally excited states of symmetric bond stretching and bending modes of $\mathrm{C}{\mathrm{O}}_2$.

• Received 15 January 2019

DOI:https://doi.org/10.1103/PhysRevA.99.032703