ABSOLUTE TOTAL CROSS-SECTIONS FOR THE CHARGE-TRANSFER AND DISSOCIATIVE CHARGE-TRANSFER CHANNELS IN THE COLLISIONS OF O+(4S)+H2

Absolute total cross sections for the reactions, O+ ( 4S) + H2(X 1Σg +)→O+H2+ [reaction (1)] and O + H + H + [reaction (2)] have been measured in the center-of-mass collision energy (Ec.m.) range of 1.33-22.22 eV. The appearance energies for H2+ (1.70±0.10 eV) and H+ (4.50±0.10 eV) are in excellent agreement with the thermochemical thresholds for reactions (1) and (2), respectively. At Ec.m. higher than approximately 9 eV, the total cross sections for reactions (1) and (2) are greater than that for the exothermic channel forming OH+ + H. © 1991 American Institute of Physics.