The magnified threshold energy range of the cross section of Sn6 +
Figure 4. The magnified threshold energy range of the cross section of Sn6 +. Same notation as in figure 2. The vertical arrows indicate the energies of the predicted ground-state ionization threshold (arrow a), of the experimental threshold of the ground-state electron configuration (arrow b) and of an onset for calculated EA contributions (arrow c).
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.