Electron-ion coincidence spectroscopy on atomic barium in the excitation range of the 4dgiant resonance

For the first time a free metal atom has been investigated by analyzed electron-ion coincidence spectroscopy after inner-shell excitation with synchrotron radiation. Probabilities of the decay from different Ba⁺ inner-hole states (4d^-1, 5s^-1, 5p^-1) to higher charged ions (Ba²⁺, Ba³⁺, Ba⁴⁺) have been determined, which allows a direct link between electron and ion spectroscopy results. Comparison between the different data sets and Hartree-Fock calculations for N₄₅ Auger transitions yields new knowledge about direct double ionization processes, e.g., their dominance on 4d^-1 Auger decay.