He-like hole states in mid-Z atoms studied by high-resolution K X-ray spectroscopy

High-resolution measurements of the K alpha(1,2) X-ray spectra were perform ed with a bent crystal diffraction spectrometer for zirconium, niobium, mol ybdenum and palladium targets bombarded by 280 and 360 MeV oxygen ions. The energy differences between the K alpha(1,2) diagram and the K(h)alpha(1,2) hypersatellite transitions as well as the intensity ratios I(K(h)alpha(1)) /I(K(h)alpha(2)) were determined. The L-shell satellites of the diagram and of the hypersatellite lines were resolved. The data are interpreted in ter ms of the properties of He-like hole states in mid-Z atoms. The Breit inter action correction is determined. The corrections due to the unresolved M-sh ell satellites and to the QED are found to be much smaller than the Breit t erms and comparable to the experimental accuracy. (C) 1999 Published by Els evier Science B.V. All rights reserved.