Ion Momentum Imaging Study of the Ion–Molecule Charge Exchange Reaction of Ar+ + CO2

Three-dimensional ion momentum imaging is developed in a combination of ion velocity map imaging technique and delay-line anode ion detection, and applied for the ion-molecule charge exchange reaction between Ar+ and CO2. In a center-of-mass collision energy range of 7.23 - 15.96 eV, CO2+ products are primarily populated at the ground state X2Πg and the single-electron excited states A2Πu, B2Σu+, and C2Σg+; the multi-electron excited states of CO2+ are also found at the higher collision energies. The production efficiency profiles of CO2+ are distinctly different from the photoionization electron spectrum of CO2, implying that the charge transfer from Ar+ would be not so fast as expected. The strong electron correlations in the short-lived intermediate (Ar-CO2)+ should be responsible for the CO2+ yields at the multi-electron excited states.