Electron-impact-inducedKplusMshell ionization in solid targets of medium-Zelements studied by means of high-resolution x-ray spectroscopy

The K${\mathrm{\beta }}_2$ x-ray spectra of zirconium, niobium, molybdenum, and palladium bombarded by 150 and 300 keV electrons were measured with a high-resolution transmission curved crystal spectrometer. Multiconfiguration Dirac-Fock calculations were used for the decomposition of the experimental spectra into the K${\mathrm{\beta }}_2$ ${\mathit{M}}^0$ (diagram) and K${\mathrm{\beta }}_2$ ${\mathit{M}}^1$ (satellite) components. The probabilities of energy dependent (direct Coulomb and two-step) processes were estimated from the differences in the satellite line yields for electrons and photons. The satellite yields are found to be considerably enhanced in comparison with those for the proton-induced ionization recently measured and analyzed in the same way [T. Ludziejewski et al., Phys. Rev. A 52, 2791 (1995)]. This result indicates the importance of multielectron effects in the K plus M shell ionization by energetic projectiles. © 1996 The American Physical Society.