Thermal energy reactions involving Ar+ monomer and dimer with N2, H2, Xe, and Kr

Rates and products of reaction are reported for the thermal energy charge transfer of Ar+ and Ar+2 with N2, H2, Xe, and Kr using a selected ion flow tube (SIFT). New rate coefficients were measured for the reactions Ar++Xe→Xe++Ar, Ar+2+N2 →Ar+⋅N2+Ar, Ar+2+H2 →ArH++H+Ar, and Ar+2+H2 →ArH+2+Ar; the rates are 4.3×10−13, 2.2×10−10, 3.6×10−10, and 1.1×10−10 cm3/s, respectively. The finding of (Ar⋅N2)+ as the product of the reaction of Ar+2 with N2 shows the bond energy of Ar+⋅N2≥1.27 eV in agreement with other techniques. In the case of H2, two reaction products are observed for reaction with Ar+2: ArH+ (85±10%) and ArH+2, but not Ar2H+ as suggested by earlier studies. Lower limits for the proton affinity of Ar (3.69 eV) and the dissociation energy for H+2⋅Ar (0.97 eV) are determined from the present work. Considering all the reaction rates, the proximity of the recombination energy of Ar+ and Ar+2 to a band in the photoelectron spectrum of a specific neutral reactant offers an explanation for the observed ordering of the relative rates of the monomer and dimer reactions.