Electron-impact single and multiple ionization of praseodymium ions

Abstract

Using the dynamic crossed-beams method, the following absolute cross sections σq,q+n for single (n=1), double (n=2) and triple (n=3) ionization by electron impact have been measured for the reaction e−+Prq+→Pr(q+n)++(n+1)e−n=1:σ2,3σ3,4σ4,5σ6,7σ7,8σ8,9σ11,12n=2:σ1,3σ2,4σ3,5σ4,6n=3:σ1,4σ2,5σ3,6The measurements have been performed in an energy range from the respective threshold up to 1 keV. For the single-ionization cross sections, contributions from excitation–autoionization processes increase with increasing charge state of the parent ion. As no theoretical calculations on praseodymium ions exist, these cross sections are compared to the semi-empirical Lotz formula [Zeitschrift für Physik 232 (1970) 101]. Where contributions of indirect inner-shell processes to the cross section are expected, we conducted energy-scan measurements with high energy resolution. For multiple ionization, no theoretical calculations on praseodymium ions exist. Therefore, the measured cross sections were compared to the semi-empirical formulae by Bélenger et al. [J. Phys. B: At. Mol. Opt. Phys. 30 (1997) 2667] and Fisher et al. [J. Phys. B: At. Mol. Opt. Phys. 28 (1995) 3027].