Magnified view of the energy-scan data for Sn4 + normalized on the absolute cross-section values
Figure 13. Magnified view of the energy-scan data for Sn4 + normalized on the absolute cross-section values. The horizontal arrows show energy ranges, where, according to the calculations, the indicated processes occur. The vertical arrow shows the threshold for the removal of two electrons from the 4p subshell. The inset magnifies the region, where the threshold of the double excitation of the 4s subshell is expected.
Electron-impact single-ionization cross sections of Snq + ions in charge states q = 4–13 with 4d[10 − (q − 4)] outer-shell configurations have been studied in the energy range from the corresponding thresholds up to 1000 eV. Absolute cross sections and fine-step energy-scan data have been measured employing the crossed-beams technique. Contributions of different ionization mechanisms have been analysed by comparing the experimental data with calculations employing the configuration-averaged distorted wave approximation. Ionization plasma rate coefficients inferred from the experimental data are also presented.