The K, L, and higher atomic shell x‐ray fluorescence yield measured data, covering the period 1978 to 1993, following the major previous compilations by Bambynek et al. (1972) and Krause (1979), are reviewed. An annotated bibliography of x‐ray fluorescence yield measurements, analyses, fits and tables 1978–1993 is presented. Comparisons of the fluorescence yields ωk, ωL, and ωM, based on measurements, and on theoretical models, are presented. Values of ωK, ωL, and ωM, fitted to standard empirical parametric formulations, are presented. In addition, selected well‐characterized measured ωK, ωL, and ωM results restricted to the period 1978–1993 are listed. These selected measured values are fitted by least squares to polynomials in Z of the form ∑nanZn and compared with theoretical and with earlier fitted values. A section on application of fluorescence yield data to computations of x‐ray energy‐absorption coefficients is included.

A Review, Bibliography, and Tabulation of K, L, and Higher Atomic Shell X‐Ray Fluorescence Yields

Cross-sections for the production of Ll, Lα, Lβ and Lγ x-rays in 22 elements (57 ≤ Z ≤ 92) by photons of 13 different energies in the range 8–50 ke V are reported. The experimental values of the cross-sections were determined by measuring the absolute yield of L subshell x-rays emitted from a target of a given element and thickness when it was bombarded with a known flux of photons of given energy. The theoretical values of the cross-sections were calculated from the theoretical/semi-empirical values of subshell photoionization cross-sections, fluorescence yields, Coster-Kronig transition probabilities, intra-shell transition probabilities and radiative decay rates. The present and previous measured and calculated values of the cross-sections are tabulated to bring out the existing status of L x-ray production cross-sections.

Ll, Lα, Lβ and Lγ X-Ray Production Cross-Sections in Elements 57 ≤Z ≤ 92 by 8-50 ke V Photons

Total L X-ray fluorescence (XRF) cross sections have been measured for ten elements in the atomic range 41 ≤ Z ≤ 52 at 5.96 keV. It is observed that the measured L XRF cross-section values for the elements in this region are in general agreement with the theoretical ones evaluated using L Subshell fluorescent yields (ωi) and Coster-Kronig transition probabilities (ƒ ij ) based on the Relativistic Dirac-Hartree-Slater theory. The average L shell fluorescence yields ( ω L ) have also been computed using the presently measured cross-section values and the theoretical L shell photoionisation cross-section values.

Measurements of L X-ray fluorescence cross sections and yields for elements in the atomic range 41 ≤ Z ≤ 52 at 5.96 keV

L l , L α , L β and L γ X-ray production cross sections have been measured in the atomic range 79≤ Z ≤92 at 59.5 keV by measuring differential cross-sections. The experimental values of the cross-sections were determined by measuring the absolute yield of L subshell X-rays emitted from a target of a given element and thickness when it was bombarded with a known flux of photons of given energy. The theoretical values of the cross-sections were calculated from the theoretical values of subshell photoionization cross-sections, fluorescence yields, Coster-Kronig transition probabilities and radiative decay rates. The enhancement effect of Coster-Kronig transition have been calculated of these elements at same energy. Coster-Kronig processes are radionless transitions in which an inner-shell vacancy is transferred from one subshell of an atom to another that is less tightly bound, both belonging to the same principal shell. Experimental measurements were carried out on a few elemental samples to examine the effect to Coster-Kronig transitions on fluorescence cross-sections for the L subshell X-ray lines using 59.5 keV for excitation. Absolute values of the L subshell X-ray cross-sections were also calculated with incorporation of the enhancement due to the Coster-Kronig effect for the elements in the range 79≤ Z ≤92 at the same excitation energy. The present results are compared with the other experimental and theoretical values.

Measurement of cross-sections and Coster-Kronig transition effect on L subshell X-rays of some heavy elements in the atomic range 79≤Z≤92 at 59.5 keV

L X-ray fluorescence cross sections ( sigma L( alpha ), sigma L( beta ) and sigma L( gamma )) and relative intensities (IL( beta )/IL( alpha ), IL( gamma )/IL( alpha )) for Ho, Er and Yb have been measured at six excitation energies in the energy range 11-41 keV. A comparison between the experimental results for the L X-ray fluorescence cross sections and the theoretically calculated values shows that the experimental results are, in general, higher than the theoretical values. However, the measured results of intensity ratios are in good agreement with the theoretical values. To the best of the authors' knowledge, photon-induced L X-ray fluorescence cross sections for these elements at different energies are being reported for the first time.

https://iopscience.iop.org/article/10.1088/0022-3700/19/11/016/pdf

Measurement of L X-ray fluorescence cross sections and relative intensities for Ho, Er and Yb in the energy range 11-41 keV

Ll, L\ensuremath{\alpha}, L\ensuremath{\beta}, and L\ensuremath{\gamma} x-ray-production cross sections have been measured in elements Ta, W, Au, Hg, Tl, Pb, Bi, Th, and U for 60-keV photons. The measured values have been interpreted in terms of photoelectric cross sections, fluorescence yields, Coster-Kronig transition probabilities, and radiative decay rates. A fairly good agreement is found between the experimental and calculated values.

Measurement of Ll, L alpha, L beta, and L gamma x-ray-production cross sections in some high-Z elements by 60 keV photons.

The L-shell X-ray intensity ratios I(Lalpha )/I(Ll), L(Lalpha )/I(Lbeta ) and I(Lalpha )/I(Lgamma ) in Au, Pb, Th and U at various photon energies 15<or=E<or=60 keV have been measured and their energy dependence is studied. A comparison of the experimental values is made with those calculated using the X-ray emission rates and subshell photoelectric cross sections from Schofield (1973), subshell fluorescence yields and Coster-Kronig transition probabilities from Chen and Crasemann (1981), Krause et al. (1978), McGuire (1971) and Rao et al. (1969, 1971). Fairly good agreement is observed between the present experimental results and the calculations, within the uncertainties of the determinations. To the best of the authors' knowledge, the results in the elements Pb, Th and U, at the present experimental energies, are reported for the first time.

Energy dependence of photon-induced L-shell X-ray intensity ratios in some high-Z elements

The angular dependence of emission intensity of L shell X-rays induced by 59.57 keV photons in Pb and U is investigated by measuring the normalized intensities of the resolved L X-ray peaks at different angles varying from 40° to 120°. It is observed that while L
 l
 and Lα X-ray peaks (originating fromJ = 3/2 state) show some anisotropic angular distribution, the emission of Lβ and Lγ X-ray peaks is isotropic. The present results contradict the calculations of Co-oper and Zare (1969) that after photoionization of inner shell, the vacancy state has equal population of magnetic substates and the subsequent X-ray emission is isotropic but confirm the predictions of Fluggeet al (1972) that the atomic inner shell vacancies produced after photoionization are aligned and the x-ray emission from the filling of vacancies in state withJ ⩾ 3/2 is anisotropic.

Experimental investigation of angular dependence of photon induced L-shell X-ray emission intensity

The cross-sections for the production of L and M shell x-rays in some elements by 5.959 keV photons have been measured in order to provide data for use in photon-induced x-ray fluorescence analysis. An attempt has been made to interpret the experimental data in terms of the theoretical sub-shell photoionization cross-sections, fluorescence and Coster–Kronig yields wherever available. In general, an agreement between the experimental and calculated values was found for the L shell. However, for the M shell, sufficient data for comparison were not available.

Measurement of L and M shell x-ray production cross-sections by 6 keV photon

The average M-shell fluorescence yields ω M in Au, Pb, Th and U have been measured using the photoionization of the M shell by 5.9 keV X-rays from a 55Fe radioactive source and analyzing the M X-rays by a Si(Li) low-energy photon spectrometer. A comparison of the results is made with the existing experimental data and the values estimated from the subshell fluorescence yields calculated by McGuire, wherever possible. The measurement for Th is reported for the first time.

K Shatendra

Papers

Measurement of Ll, L alpha, L beta, and L gamma x-ray-production cross sections in some high-Z elements by 60 keV photons.

Energy dependence of photon-induced L-shell X-ray intensity ratios in some high-Z elements

Experimental investigation of angular dependence of photon induced L-shell X-ray emission intensity

Measurement of L and M shell x-ray production cross-sections by 6 keV photon

Measurement of average M-shell fluorescence yields in some high Z elements