Soft-x-ray spectroscopy of Δn=0,n=3 transitions in highly stripped lead

Abstract
We report on n=3 to n=3 soft-x-ray transitions from the highest nuclear charge (Z=82) Na-like ions yet obtained. The results are tied to accurate calculations including screened QED contributions and confirm theoretical trends observed by Kim et al. [Phys. Rev. A 44, 148 (1991)]. Weak Ne-like and Mg-like lines are observed in an accelerator-based experiment in the energy range near 800 eV and compared to multiconfiguration Dirac-Fock calculations.