Electron-impact multiple ionization of singly and multiply charged molybdenum ions

Cross sections for electron-impact double ionization of ions in charge states q = 1-6 as well as triple ionization for charge states q = 1-4 have been measured using the crossed-beams technique covering the entire range from the respective threshold up to energies well beyond maximum. The results are compared with the scaling law of Fisher et al and the semi-empirical formula published by Shevelko and Tawara, respectively. A comparison between experimental data and those formulae shows that a further improvement of the semi-empirical approaches is necessary. Together with previously obtained data for single ionization of molybdenum ions, the measured cross sections are used to study the influence of multiple ionization on the charge-state evolution if molybdenum ions are exposed to an electron flux at 700 eV energy.