L-subshell ionization of Bi, Au, and Yb induced by F ions at intermediate velocities - art. no. 012713

We have measured the absolute cross sections for the L-subshell ionization for Yb, Au, and Bi induced by intermediate and low-energy F ions. A compara tive study of the different methods of extracting the vacancy production cr oss sections from the L x-ray line intensities is presented. The measured c ross sections are compared with the available theoretical calculations base d on the perturbed stationary state (PSS) approximation including the effec ts due to the increased binding energy, Coulomb (C) deflection, energy (E) loss, and the relativistic (R) wave function (ECPSSR). In the case of Yb an d Au targets, the ratio of the subshell ionization cross section for L-1 to that for L-2 is found to be larger than 1.0 contrary to theoretical predic tions, whereas the ratio is less than 1.0 for Bi, as expected. Similar rati os for the L-2 to L-3 subshells are, however, in agreement with the theoret ical predictions for all three targets. These observations can be understoo d in terms of the multiple vacancies in the outer shells and their effect o n the fluorescence yields and Coster-Kronig transitions. In the case of L-1 ionization, the ECPSSR calculations are found to fall much below the exper imental data for Yb and Au, and a part of the deviation is understood to be due to the existence of multiple vacancies in the outer shells and the int erplay between the Coster-Kronig and radiative transition probability. Quan titative estimates on the enhancement in the effective fluorescence yields of the L-1 subshell are also provided for all three targets.