Coster-Kronig and fluorescence yields for the L2and L3subshells in the high-Z region

Abstract

High resolution intrinsic Ge(HP) and Si(Li) X-ray detectors have been used in coincidence to determine L2 and L3 subshell fluorescence and Coster-Kronig yields at Z=86, 88, and 94. The results are: nu 2=0.498+or-0.028, omega 2=0.459+or-0.025, f23=0.105+or-0.011, omega 3=0.384+or-0.020 at Z=86; nu 2=0.516+or-0.036, omega 2=0.493+or-0.030, f23=0.053+or-0.026, omega 3=0.408+or-0.027 at Z=88; and nu 2=0.627+or-0.036, omega 2=0.513+or-0.022, f23=0.226+or-0.016, omega 3=0.509+or-0.029 at Z=94. Together with previously published data, these results provide evidence that in the L2-L3 Coster-Kronig process, ejection of an M5-subshell electron is energetically possible at Z=92 and that M4- and M5-subshell electron ejection are both possible at Z=94. These conclusions are shown to be consistent with the L X-ray line width measurements of Merrill and DuMond (1961) and with the formula put forward by Coster and Kronig (1935) for the ejected electron energy. Recent theoretical predictions of the L-subshell yields compare favourably with experiment, except when Coster-Kronig transitions close to an energy threshold are involved.