L-shell ionization of selected medium-Zelements by 0.22–0.83-MeV u−1carbon ions

Abstract

Individual $L$-shell x-ray production cross sections were measured with ${}^{12}$C ions in the energy range 0.22-- 0.83 MeV u${}^{\ensuremath{-}1}$ on Cd, In, Sb, Te, Ba, Tb, and Yb targets. From these measurements the $L$-subshell ionization cross sections were extracted and compared with the predictions of the direct ionization theories, i.e., with perturbed stationary state theory with energy loss, Coulomb deflection and relativistic corrections, the semiclassical approximation (SCA) in the united-atom limit, and SCA coupled-channel calculations involving a few lowest lying states. Better overall agreement between experiment and theory was found for the SCA theory. Inclusion of the SCA coupled-channel calculations improved the agreement for the ${L}_{2}$-subshell in the very adiabatic region, but theory fails to describe ${L}_{1}$-ionization cross sections, especially in the 0.4 $<{\ensuremath{\xi}}_{{L}_{1}}<$ 0.7 region. The degree of multiple ionization of outer shells caused by C ion bombardment was estimated from the x-ray line energy shifts and by comparing the x-ray intensity ratios for carbon ions and protons.