L-SUBSHELL IONIZATION OF RARE-EARTH ELEMENTS BY CARBON ION-BOMBARDMENT

Measurements of L-shell x-ray production cross sections and correspond ing L-subshell ionization cross sections for selected rare earth eleme nts (57 less-than-or-equal-to Z less-than-or-equal-to 68) have been pe rformed for C-12 and C-13 ion impact with energies 0.4-2.8 MeV amu-1. The influence of target thickness and projectile charge state on L-sub shell ionization is examined experimentally. The measured L-subshell i onization cross sections are compared with the predictions of the ECPS SR and SCA theories. Strong underestimation of the experimental data i n the low energy range by both theories is caused by the second-order effects not accounted for in the theoretical description, An agreement of the data with the theoretical predictions is improved by using the 'united atom' limit for the effective binding energies.