Testing relativistic atomic structure and bound-state quantum electrodynamics with Co-like ions*

High-Z highly charged ions are known to exhibit enhanced relativistic and quantum electrodynamics (QED) effects. Such ions with a single hole in closed shells have suppressed electron correlations and are proposed for testing relativistic atomic structure and bound-state QED [1-4]. Particularly interesting examples are the ground state configuration of 2p⁵ (F-like), 3d⁹ (Co-like), and 4f¹³ (Pr-like) ions. Here we present our measurements of the 3d^{9 2}D_3/2 - ²D_5/2 fine-structure splitting of Co-like ions of Yb, Re, Os, and Ir performed with an electron beam ion trap [5]. We also report relativistic many-body perturbation theory and multiconfiguration Dirac-Hartree-Fock calculations and their comparison with the measurements and other theoretical results.

[1] R. Si, X. L. Guo, T. Brage, C. Y. Chen, R. Hutton, and C. F. Fischer, Physical Review A 98,012504 (R) (2018).

[2] M. C. Li, R. Si, T. Brage, R. Hutton, and Y. M. Zou, Physical Review A 98, 020502 (2018).

[3] G. O’Neil et al, Physical Review A 102, 032803 (2020).

[4] M.C. Li, G.L. Zhu, K. Wang, R. Si, C.Y. Chen, T. Brage, R. Hutton, Journal of Quantitative Spectroscopy & Radiative Transfer 287 108215 (2022).

[5] J. D. Gillaspy, Phys. Scr. T 71, 99 (1997).