Effect of electron-electron interaction on projectile K-shell ionization in energetic ion-atom collisions studied by 0° Auger electron spectroscopy

Abstract

Cross sections for 1s ionization of the ground state of O 4(1s 22s 2) were obtained in 10–30 MeV collisions of O 4+ with H 2 and He targets. High resolution Auger electron spectroscopy was used to detect at 0° with respect to the beam direction, the electrons emitted from the Auger decay of O 5+ (1s2s 2) → O 6+ (1s 2) + e − following 1s ionization of the O 4+ ions. The electron-nucleus ( σ enI) and electron-electron ( σ eeI) ionization cross sections, due to ionization of the projectile electron either by the target nucleus or the target electrons, respectively, were independently computed. σ enI was calculated within a PWBA treatment, while σ eeI was computed within an impulse approximation (IA) treatment of electron impact ionization of O 4+. The incoherent sum σ enI + σ eei was found to be in good agreement with the data. K-shell ionization of the metastable O 4+(1s 22s2p 3P) component of the beam was also observed.