Reactions of H2O+ and D2O+ with Molecular Hydrogen. I. Proton Affinity of Hydrogen

The cross section of the ion molecule reaction H2O++H2→ H3++OH and its deuterium counterpart was studied over an energy range 2–100 eV using a tandem mass spectrometer. The measurements permitted a determination of the proton affinity of H2 of 4.37± 0.05 eV and 4.50± 0.05 eV for D2. The energy threshold values indicate that the reaction is proceeding by complex formation at low energies.