Electron-impact single ionization of the ${\mathbf{Se}}^{3+}$ ion

Single ionization by electron impact of the ${\mathrm{Se}}^{3+}$ ion is investigated in the Dirac-Fock-Slater approximation. Contributions from direct ionization (DI), excitation-autoionization, and resonant-excitation double-autoionization processes are taken into account. Good agreement with the experiment is obtained at the lower energies of the incident electron when the DI process is considered in the potential of the ionizing ion. On the other hand, the potential of the ionized ion has to be used for the higher energies of the electron. It is shown that ionization-ionization and ionization-excitation-ionization processes can play the significant role in the double ionization of ${\mathrm{Se}}^{3+}$ ions.

Figure 1

Energy levels (a) and subconfigurations (b) of four lowest configurations and configurations that straddle the ionization threshold for the ${\mathrm{Se}}^{3+}$ ion. The ground and first excited configurations of ${\mathrm{Se}}^{4+}$ are also presented. Red (light)—even configurations; blue (dark)—odd configurations.

Figure 2

Single ionization cross sections for the DI, EA, and REDA processes. Experiment: open circles with error bars [9]. Logarithmic scale is used for electron energies.

Figure 3

Comparison of the total single-ionization cross sections (DI+EA). Our LLDW data are obtained in the potential of the ionized (green solid) and ionizing (red dashed) ions; dotted line (black) represents CADW values [14] and dashed-dotted line (blue) represents LLDW [15]. Experiment: open circles with error bars [9]. Logarithmic scale is used for electron energies.

Figure 4

Comparison of contribution from the DI and EA channels for single ionization of ${\mathrm{Se}}^{3+}$. Logarithmic scale is used for electron energies.

Figure 5

REDA cross sections corresponding to DC to $3d^{9}4s^{2}4p5l5l^{\prime }$ ($l,l^{\prime }=0\text{–}4$) configurations. Solid line (green) represents level-to-level calculations; dotted line (red) represents values for subconfigurations which are shifted by 1.6 eV to the higher-energy side for better agreement with the level-to-level data.

Figure 6

Single-ionization cross sections obtained in the potential of ionized (green solid) and ionizing (red dashed) ion. Experiment: open circles with error bars [9]. Logarithmic scale is used for electron energies.

Figure 7

Single-ionization cross sections obtained in the potential of ionized ion (red dashed) with subtracted experimental cross sections from double-ionization process (green solid). Experiment: open circles with error bars [9]. Logarithmic scale is used for electron energies.

Figure 8

Single-ionization cross sections obtained in the potential of ionized (green solid) and ionizing (red dashed) ion with subtracted experimental cross sections from double-ionization process. Experiment: open circles with error bars [9]. Logarithmic scale is used for electron energies.