Cross section ratios of double-to-single K-shell ionization induced by electron impact in metallic Sc, Cr and Cu targets

Abstract

The double K-shell ionization of Sc, Cr and Cu induced by electron impact was investigated via high energy resolution measurements of the Ka diagram transitions and the transitions resulting from the radiative decay of K-shell double vacancy states, namely the Kha hypersatellites. For Sc, the Kj3 diagram lines and Khj3 hypersatellites were also measured. The measurements were carried out in-house with a von Hamos curved crystal spectrometer operated in the so-called direct geometry in which the anodes of Sc, Cr and Cu X-ray tubes were used as targets. For each element, the electron kinetic energy was chosen to be about twice the threshold energy for the double l s ionization. The double-to-single ionization cross-sections ratios PKK were deduced from the hypersatellite-to-diagram line yield ratios, corrected beforehand for the self-absorption of the X-rays in the target and the energy dependent efficiency of the spectrometer. The obtained ratios are discussed and compared to other PKK values found in the literature for electrons and photons.

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

“…For the K h α hypersatellite lines, in particular, in the case of 3 d transition metals, such discrepancies have been already observed (see, e.g.,the studies of Hoszowska et al and Diamant et al). From the reported K h β 1,3 hypersatellite spectra plots for Sc, Ti, and Fe, one can derive FWHM widths of about 7, 8, and 15 eV, respectively. The FWHM of Sc (Z=21) and Ti (Z=22) are comparable with the FWHM of 8.8 eV obtained in this work for Cr (Z=24), whereas the value found for Fe (Z=26) seems to be unexpectedly high as compared with those of the three lighter elements.…”