Absolute cross sections for O_2 dication production by electron impact

摘要

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)O_2 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 O_2 ~(++) is mainly produced through post-collisional Auger-like deexcitation.