Vacancy sharing between the L-subshells of Th under heavy ion impact

Thorium L X-rays induced by 0.5 – 2.5 MeV/amu Be, C, F, Mg, Si and S ion impact have been measured. L-subshell ionization cross section ratios, corrected for multiple ionization effects, have been derived. The comparison with first order ionization theories reveals systematic discrepancies which are attributed to vacancy sharing between the L-subshells during the collision. Coupled-channel calculations for vacancy sharing qualitatively account for the behaviour found experimentally.