The production of CO⁺(A ²Π) from dissociative ionization of CO₂: A fragment ion-photon coincidence spectroscopic investigation

Fragment ion-photon coincidence (FIPCO) spectra by 120 eV electron impact on carbon dioxide (CO₂) have been observed, in which optical emission in the 250-600 nm region has been detected. There are a dominant CO₂⁺ peak and a weak, broad CO₊ peak in the FIPCO spectra. The kinetic energy distribution of CO⁺ correlated with the CO⁺(A ²Π-X ²Σ⁺) emission has been estimated on the basis of the Monte Carlo simulation of the CO⁺ band shape. This CO⁺(A ²Π) ion is produced through the dissociation process, CO₂ + e^- → CO₂⁺*[MET I ²Π_u] + 2e^- → CO⁺(A ²Π) + O(³P) + 2e^-, where MET refers to multiple electron transitions. The production of CO⁺(B ²Σ⁺) is negligible compared with that of CO⁺(A ²Π). The produced CO⁺(A ²Π) ions is in vibrationally excited levels, and there is little population in the vibrational levels, v′ ≤ 3.