Ejected-electron spectra from the triplet states of O⁴⁺(1s²3l3l') produced by O⁶⁺+O₂collisions

Abstract

Ejected electrons from the triplet states of doubly excited O⁴⁺ ions, produced by 60 keV O⁶⁺+O₂ collisions, have been measured with high resolution zero-degree electron spectroscopy. The triplet states of doubly excited configurations are selectively produced through double electron transfer processes with the O₂ molecular target under single collision conditions. Electrons ejected from the 1s²2pnl and 1s²3lnl′ configurations are observed over a wide energy range. Ejected-electron spectra from the O⁴⁺(1s²3l3l') are compared with theoretical calculations. The calculation of energy levels of 1s²3l3l' states has been carried out by the Z-expansion method, where Z is the nuclear charge. Correlation, relativistic and radiative effects are taken into account. Electrons from triplet states are identified by comparison with the calculations and the 'singlet state' spectrum produced by O⁶⁺+He collisions.