Diagram, valence-to-core, and hypersatellite Kβ X-ray transitions in metallic chromium

We report on measurements of the Kβ diagram, valence-to-core (VtC), and hypersatellite X-ray spectra induced in metallic Cr by photon single and double K-shell ionization. The experiment was carried out at the Stanford Synchrotron Radiation Lightsource using the seven-crystal Johann-type hard X-ray spectrometer of the beamline 6-2. For the Kβ diagram and VtC transitions, the present study confirms the line shape features observed in previous works, whereas the K h β hypersatellite transition was found to exhibit a complex spectral line shape and a characteristic low-energy shoulder. The energy shift of the hypersatellite relative to the parent diagram line was deduced from the measurements and compared with the result of extensive multiconfiguration Dirac–Fock (MCDF) calculations. A very good agreement between experiment and theory was found. The MCDF calculations were also used to compute the theoretical line shape of the hypersatellite. A satisfactory agreement was obtained between the overall shapes of the experimental and theoretical spectra, but deviations were observed on the low- and high-energy flanks of the hypersatellite line. The discrepancies were explained by chemical effects, which were not considered in the MCDF calculations performed for isolated atoms.

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The financial support of the Swiss National Science Foundation (Grant No. 200020-146739) is acknowledged by F.?Z., J.?H., and J.-Cl.?D. M.?G. acknowledges the support of the FCT, under the Contract No. SFRH/BPD/92455/2013 and the project PTDC/FIS-AQM/31969/2017, ?Ultra-high-accuracy X-ray spectroscopy of transition metal oxides and rare earths.? This work was also partly supported by the research center grants nos. UID/FIS/04559/2013 to LIBPhys-UNL, and UID/MULTI/04046/2013 to BioISI, from the FCT/MCTES/PIDDAC.