Optical spectroscopy of complex open 4$d$-shell ions   Sn$^{7+}$-Sn$^{10+}$
  We analyze the complex level structure of ions with many-valence-electron open [Kr] 4$d^\textrm{m}$ sub-shells ($\textrm{m}$=7-4) with ab initio calculations based on configuration-interaction many-body perturbation theory (CI+MBPT). Charge-state-resolved optical and extreme ultraviolet (EUV) spectra of Sn$^{7+}$-Sn$^{10+}$ ions were obtained using an electron beam ion trap. Semi-empirical spectral fits carried out with the orthogonal parameters technique and Cowan code calculations lead to 90 identifications of magnetic-dipole transitions and the determination of 79 energy ground-configuration levels, questioning some earlier EUV-line assignments. Our results, the most complete data set available to date for these ground configurations, confirm the ab initio predictive power of CI+MBPT calculations for the these complex electronic systems. 
F. Torretti (1 and 2), A. Windberger (1 and 3), A. Ryabtsev (4 and 5),   S. Dobrodey (3), H. Bekker (3), W. Ubachs (1 and 2)...
physics.atom-ph