Electron-impact dissociation and ionization of OH⁺ and OD⁺ ions

Abstract

Absolute cross sections for electron impact ionization and dissociation of OH⁺ and OD⁺ leading to the formation of the OH²⁺, O⁺, O²⁺, O³⁺ and D⁺ ions have been measured by applying the animated electron-ion beam method in the energy range from the respective reaction thresholds up to 2.5 keV. The maximum of the single ionization cross section is found to be (0.95  ±  0.02) × 10⁻¹⁹ cm² at 155 eV. The maximum total cross sections for O⁺ and D⁺ fragments production are observed to be (15.7  ±  0.2) × 10⁻¹⁷ cm² at 95 eV and (10.8  ±  0.5) × 10⁻¹⁷ cm² at 95 eV, respectively. The cross sections for O²⁺ and O³⁺ are much smaller, (5.37  ±  0.04) × 10^-18 cm² at 135 eV and (7.95  ±   0.23) × 10^-20 cm² at 315 eV, respectively. The collected data are analyzed in details in order to determine separately the contributions of dissociative excitation and of dissociative ionization to the O⁺ and D⁺ fragments production.