The proton transfer from ArH+ to various neutrals

The proton transfer reactions from ArH+ to H2, D2, CH4, N2, O2, CO, CO2, and the corresponding deuteron transfer reaction of ArD+ with H2 and D2 have been investigated in a drift tube with mass selected ion injection. The use of helium and argon buffer gases permits a qualitative assessment of vibrational energy effects along with a quantitative assessment of the influence of translational energy on reaction rates. These exothermic reactions all proceed with large rate coefficients which approach the collision rates for the respective reactants. All except the reaction of ArH+ with H2 (D2) were independent of translational energy over the range investigated. In an argon buffer equilibrium is readily established for the reaction ArH++H2⇄H3++Ar. A treatment of the center-of-mass kinetic energy as a ’’translational temperature’’ permits the construction of a van’t Hoff plot for this reaction from which a value of Δ(PA)=0.55 eV is obtained, which is consistent with the accepted proton affinities of H2 and Ar.