**Figure 7.** The present single-ionization cross section of Sn^{8 +} compared to the results of the present CADW calculations. Same notation as in figure 2. The brackets with arrows denote energy ranges, where REDA processes involving 3d-subshell excitations are to be expected. The brackets with arrows denote energy ranges, where REDA processes involving 3d- and 3p-subshell excitations are to be expected. The dark-shaded area at the bottom of the graph represents the total ionization contribution of the 4d^{5}4f excited-ion-beam component with an estimated fraction of 0.6%.

**Abstract**

Electron-impact single-ionization cross sections of Sn^{q +} 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.