The [Formula Presented] 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 [Formula Presented] 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 [Formula Presented] 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 (CTMC) 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.
|Number of pages||1|
|Journal||Physical Review A - Atomic, Molecular, and Optical Physics|
|Publication status||Published - jan. 1 2000|
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics