  The L-subshell ionization mechanism is studied in an ultra-thin osmium target
bombarded by 4-6 MeV/u fluorine ions. Multiple ionization effects in the
collisions are considered through the change of fluorescence and Coster-Kronig
yields while determining L-subshell ionization cross sections from L-line x-ray
production cross sections. The L-subshell ionization, as well as L-shell x-ray
production cross sections so obtained, are compared with various theoretical
approximations. The Coulomb direct ionization contributions is studied by (i)
the relativistic semi-classical approximations (RSCA), (ii) the shellwise local
plasma approximation (SLPA), and (iii) the ECUSAR theory, along with the
inclusion of the vacancy sharing among the subshells by the coupled-states
model (CSM) and the electron capture (EC) by a standard formalism. We find that
the ECUSAR-CSM-EC describes the measured excitation function curves the best.
However, the theoretical calculations are still about a factor of two smaller
than the measured values. Such differences are resolved by re-evaluating the
fluorescence and the Coster-Kronig yields. This work demonstrates that, in the
present energy range, the heavy-ion induced inner-shell ionization of heavy
atoms can be understood by combining the basic mechanisms of the direct Coulomb
ionization, the electron capture, the multiple ionization, and the vacancy
sharing among subshells, together with optimized atomic parameters.

Atomic Physics