Dissociative recombination of the cation and dication of CO₂

Dissociative recombination of CO₂ ions has been studied at the heavy-ion storage ring ASTRID. Electrons were scattered on both singly and doubly charged positive ions of the molecule, and the absolute cross sections were measured in the energy range of 10^-3–10¹eV. Thermal rate coefficients of α(CO₂⁺) =(6.5±1.9)×10^-7×(300/T[K])^0.8cm³s^-1 and α(CO₂²⁺) =(6.2±2.1)×10^-7×(300/T[K])^0.5cm³s^-1 were extracted. Furthermore, branching ratios for molecular breakup into neutral product channels have been measured using a grid technique. The branching ratios were measured at ∼0eV for CO₂⁺, and in the entire energy range from 10^-3eV to 50 eV for CO₂²⁺. This measurement reveals pronounced structure in the CO₂²⁺ branching ratios.