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The K␣ x-ray emission spectra of Ca, Ti, Cr, and Fe targets bombarded by 2-19-MeV/amu C, O, and Ne ions were measured by means of high-resolution crystal diffractometry. The KL N x-ray satellite lines appearing in these spectra as a result of the radiative decay of atomic states with one hole in the K shell and N in the L subshells could be resolved, and their relative intensities determined. The latter were corrected to account for the intra-atomic rearrangement processes preceding the K x-ray emission. From the values obtained the heavy ion induced L-shell vacancy distribution was then deduced for each collision. Significant deviations from the binomial distribution were observed. The discrepancies could be slightly diminished by assuming that the L-shell vacancy production is due to two uncorrelated processes: direct Coulomb ionization and target L-shell electron capture into the projectile K shell. A new KL N vacancy yield distribution model based on statistical considerations was built, which takes into account both mechanisms of vacancy production. The average direct L-shell ionization probabilities per electron related to the investigated collisions were determined by fitting this distribution to the corrected experimental L vacancy yields, employing results of three-body classical trajectory Monte Carlo ͑CTMC͒ calculations for the electron capture probabilities. The so-obtained direct ionization probabilities were found to be somewhat smaller than the ones deduced from the standard binomial distribution, especially in low-energy collisions for which electron capture is more important. It was furthermore observed that CTMC calculations significantly overestimate the direct ionization probabilities found in the present experiment. To a smaller extent, the same holds for the geometrical model predictions, whereas theoretical results from the semiclassical approximation model were found to reproduce the experimental data better.

We report on the study of heavy-ion-induced Si KL x-ray satellite spectra of several 3d, 4d and 5d silicides, with the aim of elucidating the trends in bonding properties of transition metal (TM) silicides. Measurements of the 43 MeV Ne 3+ -beam-induced Si KL spectra of elemental silicon and compound targets were performed at the Paul Scherrer Institute, Villigen, Switzerland, with a high-resolution von Hamos crystal spectrometer. The interpretation of the data was based on the importance of the effect of the solid and chemical environment on the KL x-ray satellite relative intensities due to the L-vacancy refilling by intra-and inter-atomic electron transitions. Within the framework of a statistical procedure for L-shell vacancy refilling the average L-shell rearrangement probability for each silicide was extracted so that calculated x-ray intensity distributions matched the experimental ones. The results are discussed in terms of the interplay of Si-Si, Si-TM and TM-TM bonding interactions in the studied TM silicides.