X-Ray Fluorescence Yields and Coster-Kronig Transition Probabilities of the L1, L2 and L3 Subshells of Pb

Abstract

A three-parameter technique for XX · t and Xe · t coincidence measurements was employed to acquire coincident energy spectra, singles spectra from two semiconductor detectors, and a TAC spectrum simultaneously. From analysis of the singles spectra in each detectror, the total coincidence spectra in each detector, and gated coincidence spectra in each detector, the L1, L2, and L3 subshell X-ray branching ratios (sj) and fluorescence yields (ωi), together with the Coster-Kronig transition probabilities (fij) were determined at Z = 82 from the radioactive decay of 33.4 y207 Bi. The L3 subshell values are: s3 = 0.241 ± 0.024 and ω3 = 0.302 ± 0.021; for the L2 subshell, s2 = 0.235 ± 0.024, ω2 = 0.366 ± 0.026, and f23 = 0.130 ± 0.002. Using these values of ω2 ω3, and f23 as input, the L1 subshell quantities were then determined by a direct measurement of the number of characteristic L1 subshell X-rays per initial vacancy from L X-ray spectra gated by L conversion electrons. This gives s1 = 0.346 ± 0.084, ω1 = 0.104 ± 0.019, f12 = 0.105 ± 0.026, and f13 = 0.658 ± 0.086. Uncertainties are all to 95% confidence. The experimental L-subshell values are compared with theoretical calculations reported in the literature. The f12 value confirms the predicted decrease above Z = 74 due to the absence of some of the L1-L2N Coster-Kronig transitions. The value of ω3 is smaller than the theoretical estimates, while s3 is in good agreement. The value of ω2 also is lower than theory predicts, but s2 agrees well. The measured value of f23 is somewhat larger than theory predicts, but agrees better with the more recent relativistic calculations than with older non-relativistic ones. The values of f12 and f13 are in better agreement with the relativistic calculations than with the older non-relativistic theory.