Diagram x-ray emission spectra of a hollow atom: The [formula presented] and [formula presented] hypersatellites of fe

High-resolution Fe [Formula presented] and [Formula presented] hypersatellite spectra were measured, using monochromatized synchrotron radiation photoexcitation. The lines’ energies, splitting, excitation thresholds, and the [Formula presented] intensity ratio were derived with high accuracy. Having both spectra, not hitherto available for any atom with high resolution, allows separating out the energy shifts of the outer levels caused by a [Formula presented] shell spectator vacancy. Comparison with ab initio relativistic multiconfigurational Dirac-Fock calculations reveals that while the influence of relativity and QED effects is mostly accounted for, discrepancies remain in the lines’ intensity ratio, which sensitively measures the intermediacy of the coupling. Similar discrepancies, of unknown origin, are found in the energy shifts of the outer levels due to the final-state [Formula presented] shell spectator vacancy.