Absolute state-selected and state-to-state total cross sections for the Ar+(2P3/2,1/2)+CO reactions

Abstract

Absolute spin–orbit state-selected total cross sections for the reactions, Ar+(2P3/2,1/2)+CO→CO++Ar [reaction (1)], C++O+Ar [reaction (2)], O++C+Ar [reaction (3)], and ArC++O [reaction (4)], have been measured in the center-of-mass collision energy (Ec.m.) range of 0.04–123.5 eV. Absolute spin–orbit state transition total cross sections for the Ar+(2P3/2,1/2)+CO reactions at Ec.m. have also been obtained. The appearance energies (AE) for C+(Ec.m.=6.6±0.4 eV) and O+(Ec.m.=8.6±0.4 eV) are in agreement with the thermochemical thresholds for reactions (2) and (3), respectively. The observed AE for reaction (4) yields a lower bound of 0.5 eV for the ArC+ bond dissociation energy. The kinetic energy dependence of the absolute cross sections and the retarding potential analysis of the product ions support that ArC+, C+, and O+ are formed via a charge transfer predissociation mechanism, similar to that proposed to be responsible for the formation of O+ (N+) and ArO+ (ArN+) in the collisions of Ar+(2P3/2,1/2)+O2(N2).