L-SUBSHELL IONIZATION CROSS-SECTIONS OF YB BY IMPACT OF 1.0-8.5 MEV HE-4(2+) IONS

L-subshell ionization induced by 1.0-8.5 MeV He-4(2+) was measured exp erimentally for a thin target of Yb using simultaneous acquisition of PIXE and RES yields. The data were compared with the theoretical predi ctions of the ECPSSR theory and its extensions known as the ECPSSR-IS and ECPSSR-IS-UA theories. Good agreement was found for the L-1- and L -3-subshells at energies higher than about 5 MeV, whereas a fair agree ment with the theory was observed for the L-2-subshells. Possible reas ons for the discrepancies are discussed in the framework of vacancy tr ansfer from the L-1- to the L-2- and L-3-subshells. (C) 1998 John Wile y & Sons, Ltd.