Observation of QED Effects, Breit Interaction, and Electron Correlation in Highly Charged Au Ions Produced by a...

We report on measurements of extreme ultraviolet (EUV) radiation from highly charged gold ions in laser-produced plasma to investigate the quantum electrodynamics (QED) effects, Breit interaction, and electron correlation (EC) effects which play a crucial role in determining the energy levels of high-Z, highly charged ions. Specifically, we analyze emission lines from the 4s  ^{2}S_{1/2}-4p  ^{2}P_{1/2} and 4d  ^{2}D_{3/2}-4f  ^{2}F_{5/2} transitions in Cu-like Au ions (Au^{50+}), where the ground state consists of a filled M-shell and a single 4s electron in the outermost shell. Utilizing the multiconfiguration Dirac-Hartree-Fock (MCDHF) method, we systematically calculated the energy levels and transition wavelengths. Our results show that only when QED effects, Breit interaction, finite nuclear size (FNS) corrections, and EC effects with sufficient electron configurations are included do the theoretical predictions align with experimental observations. By combining state-of-the-art experiments with high-precision computations, we resolve the long-standing discrepancies in the spectrum of Cu-like Au ions, providing the first quantitative delineation of QED effects, Breit interaction, FNS corrections, and EC effects on its energy levels. Our methodology is directly applicable to other highly charged ions, which are crucial for modeling astrophysical and laboratory plasmas.