Electron-impact single-ionization of Ar6+ ions

Electron-impact single-ionization cross sections of Ar6+ ions have been measured in the energy region from below 14 eV up to 1000 eV. Strong contributions of indirect-ionization processes involving excitation of the 2p subshell have been observed. Ions in long-lived excited states were present in the primary ion beam and resulted in ionization onsets below the ground-state ionization threshold.