Non-Dissociative Single-Electron Capture Studied for O2 2+ Ions on Ar, N2and He at 100 eV

Abstract

Energy-gain spectra for single-electron capture by O₂²⁺ions colliding with Ar, He and N₂ have been measured at an impact energy of 100 eV and 0º scattering angle by means of translational energy-gain spectroscopy. In O₂²⁺ - Ar and N2collisions, only one
peak is observed at the energy-gain around 3.5 eV, which is correlated with nondissociative single-electron capture from ground state (X¹ Σg⁺ ) of O₂²⁺ ions into the A ²Πu state of O₂⁺ . However, for the O₂²⁺ - He collision system, the dominant channels are due to
capture into the ground state X ²Πg of O₂⁺ from W ³∆u, B ³Πg and B / ³Σu metastable states of the O₂²⁺, respectively. A reasonable description of the dominant final states is obtained qualitatively in terms of the reaction windows, which are calculated using the LandauZener (LZ) model and the extended version of the classical over-the-barrier (ECOB) model. Differential cross sections for single-electron capture by 100 eV O₂²⁺ions from Ar have also been measured. The results are quantitatively explained by semi-classical model based on Coulomb potential energy curves.

Keywords: Single-electron capture; Non-dissociative electron capture; Reaction window.