Absolute cross sections for O2 dication production by electron impact

Abstract

Direct detection of homonuclear diatomic dications using mass spectrometry has the intrinsic inability to distinguish between fragments with the same mass-to-charge ratio, as is the case of the oxygen molecule. In this work, absolute cross sections for the double ionization of the homoisotopic (16)O2 molecule by electron impact, in the 30-400 eV energy range, is reported for the first time, and show significant discrepancies with previous results, obtained with the heteroisotopic (16)O(17)O. The measurements suggest that O2 (++) is mainly produced through post-collisional Auger-like deexcitation.