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.