Merged electron-ion beam experiments. V. Dissociative recombination of OH⁺, H₂O⁺, H₃O⁺and D₃O⁺

Abstract

For pt.IV see ibid., vol.14, no.8, p.1353-671 (1981). Absolute cross sections for dissociative recombination of OH+, H2O+, H3O+ and D3O+ have been measured using a merged electron-ion beam apparatus through an energy interval from 0.01 to 1 eV. The recombination cross section for the diatomic OH+ is small, one of the smallest measured by the authors for a diatomic ion. The cross sections for the polyatomics H2O+, H3O+ and D3O+ are large and nearly identical. Like most other polyatomic ions they exhibit nearly an Ecm-1 energy dependence below approximately 0.1 eV. At higher energies the slope of the cross section versus electron energy is much steeper with an energy dependence near Ecm-2. Cross sections for D3O+ are less than those for H3O+ indicating the presence of a small isotope effect.