Electron-impact single ionization of low-charged molybdenum ions

The electron-impact single ionization of low-charged Mo ions is studied both experimentally and theoretically. The absolute cross sections for Mo-q+ ions in charge states q=1-8 are measured using a crossed-beam technique. Distorted-wave calculations are made including both direct ionization and excitation-autoionization contributions. For ions in charge states q=6-8, the measured cross sections are in good agreement with calculations involving only the lowest-energy metastable configuration. For ions in charge states q=3-8, the good agreement between experiment and theory confirms the dominant role played by excitation-autoionization contributions to the total ionization cross section.