Collision dynamics of three interacting atoms: Stripping reactions of Ar++H2 and of K+I2

Abstract

Equations for stripping reaction cross sections, obtained from a multiple‐collision expansion for triatomic systems, are applied to Ar⁺+H₂ → ArH⁺+H and its isotopic substitutions, and to K+I₂ → KI+I. The equations involve the momentum distributions of reactant and product molecules, and are considered for mechanisms where stripping begins either before or after electron transfer, for both systems. Calculations of forward velocity distributions, product angular and energy distributions, isotope ratios, and total cross sections for Ar⁺+H₂ are in over‐all agreement with experiments and indicate that stripping begins after electron transfer in these systems. Comparison with experiment of calculated product angular and energy distributions and forward velocity distrubutions for K+I₂ favors a mechanism where a vertical electron transfer occurs first, with simultaneous partial vibrational relaxation of I⁻₂, followed then by stripping. Discrepancies remain however for K+I₂, suggesting some contribution from other mechanisms.