Electron-impact excitation and single- and multiple-ionization cross sections of heavy ions: Sn13+as an example

Abstract

The cross sections of electron impact with Sn${}^{13+}$ resulting in the production of Sn${}^{13+}$-Sn${}^{16+}$ are investigated theoretically by using the fine-structure-level distorted-wave approximation from the threshold to 4000 eV. The electron-impact excitation, ionization, and resonant excitation processes are included in the cross sections. Contributions from different processes are determined by independent processes and isolated resonance approximations. The decay pathways and branching ratios for single and sequentially multiple autoionization for the final autoionized states are determined by detailed calculations. The cross section forming Sn${}^{13+}$ is the largest and next are those for Sn${}^{14+}$ and Sn${}^{15+}$. The double-ionization cross section forming Sn${}^{15+}$ is smaller than that forming Sn${}^{14+}$, yet the relative magnitude is larger at higher incident electron energy. A comparison with a recent measurement for the single-ionization cross section [A. Borovik, Jr. et al., J. Phys. B 46, 175201 (2013)] showed that accurate determination of the branching ratios for single and double autoionization and including contributions of the resonant excitation double autoionization are crucial to obtain accurate results.