L₁–L₃ Coster–Kronig and L_i (i = 1,2,3) sub‐shell fluorescence yields for Th and U

Abstract

The L1–L3 Coster–Kronig yield, f13, for Th and U was determined using measured intensities of the Lα x‐rays emitted following selective ionization of the L3 sub‐shell by Mo K x‐rays (B L 3 < Einc. < B L 2) and of those emitted following ionization of the Li (i = 1,2,3) sub‐shells by the 59.54 keV γ‐rays (B L 1 < Einc. < BK), where B K/italicL italici is the K shell/Li sub‐shell ionization threshold of the target element. The measurements were performed using an energy‐dispersive x‐ray fluorescence set up involving an Si(Li) detector and photon sources consisting of an 241Am radioactive annular source used in (i) the direct excitation mode and (ii) the secondary excitation mode together with the Mo secondary exciter. In addition, the Li (i = 1,2,3) sub‐shell fluorescence yields (ωi) for Th and U were deduced using our earlier measured x‐ray fluorescence cross‐sections at incident photon energies in the range 17–60 keV and the theoretical photoionization cross‐sections. The measured f13 and ωi yields were compared with the available semi‐empirical values and the theoretical values based on relativistic Hartree–Dirac–Slater (RDHS) calculations. Copyright © 2002 John Wiley & Sons, Ltd.

Measurement of Coster–Kronig yieldsf23for W, Pt, Pb and U

“…However, in the case of U, the present value is close to the semi-empirical value, that is the Z-region with abrupt discontinuity of f 23 . The present results show comparatively fair agreement with those from earlier radionuclide [21,22] and photo ionization measurements [8,19] for W, Pt and Pb, but are found to be higher than other experimental values [23][24][25][26][27][28][29] quoted in the present table. The other experimental values are, generally, from synchrotron and coincidence measurements.…”

“…Moreover, in the K x-ray energy region of ∼9-21 keV, the transmission through air column (1.5 cm) is constant (0.99) at two extreme energies and is only affected at the third decimal place. Thus, the ratios are determined as [21]; 0.156 ± 0.010 [22]; 0.119 0.116 0.123 0.105 ± 0.011 [23]; 0.1055 ± 0.011 [24]; 0.13 ± 0.002 [25]; 0.112 ± 0.002 [26,27]; 0.115 ± 0.004 [20]; 0.091 ± 0.010 [18] U 0.158 ± 0.019 0.147 ± 0.010 [28]; 0.146 ± 0.018 [23]; 0.140 0.167 0.139 0.140 ± 0.004 [20]; 0.139 [29] the equivalent Al target of the PE. ε b Kαβ and ε a Kβ are the efficiencies of the Si-PIN detector at the K b αβ and K a β energies of PEs and are determined from the given efficiency plots of the detector by the manufacturer [17].…”

Fluorescence yields and Coster–Kronig probabilities for the atomic L subshells. Part II: The L1 subshell revisited

“…[11] is an example. The c-rays from this source are first used to excite the entire L X-ray spectrum of the element of interest.…”