Thermal-energy charge transfer of Ar+ with H2O: Internal and kinetic energy of the product H2O+

Abstract The reaction of Ar + with H 2 O has been investigated at near-thermal energy. The product ions H 2 O + and ArH + account for 90 and 10% of the total reaction rate, respectively. Kinetic energy measurements and emission spectroscopy of the H 2 O + product ions are reported. It is concluded that at least 60% of H 2 O + ions are in the X state with ≈2.4 eV vibrational energy while up to 40% are in the A state with a mean vibrational energy of 1.4 eV; the A state vibrational distribution has been determined. It is shown that both H 2 O + states are populated via an energetically “non-resonant” charge transfer process.