X-ray Fluorescence Cross-sections Research Articles

L-subshell fluorescence cross sections and L-subshell fluorescence yields in elements 68 ⩽ Z ⩽ 92 by 59.5 keV photons

L-subshell (σ1,σ2 and σ3) x-ray fluorescence cross sections were measured for Er, Ta, W, Au, Hg, Tl, Pb, Bi, Th and U at an excitation energy of 59.5 keV using a Si(Li) detector coupled to a model 4096 computerized multi-channel analyser. The values of Li-subshell fluorescence yields (ω1, ω2 and ω3) have been measured for the same elements using the previously measured cross section values and the theoretical Li-subshell photoionization cross section Coster-Kronig transition probabilities and emission rates. It is observed that the measured Li (i = 1, 2 and 3) subshell x-ray fluorescence cross section and Li-subshell fluorescence yield (ω1, ω2 and ω3) values for the elements are in general agreement with the theoretical ones evaluated using L-subshell fluorescence yields and the L-subshell photoionization cross section.

Calculation of average L shell fluorescence yields for the elements with 25≤Z≤101

Average L shell fluorescence yield\((\varpi _L )\), average L shell Auger yields\((\bar a_L )\) and the total L shell X-ray fluorescence (LXRF) cross sections (σLx) at 30 keV have been calculated theoretically for the elements with 25≤Z≤101. These calculated values have been compared with the other experimental and theoretical values.

Measurement ofKαandKβfluorescence cross sections for elements in the range44<~Z<~68at 59.5 keV

The $K\ensuremath{\alpha}$ and $K\ensuremath{\beta}$ x-ray fluorescence cross sections have been measured for elements in the range $44l~Zl~68$ at an excitation energy of 59.5-keV \ensuremath{\gamma} ray from ${}^{241}\mathrm{Am}$ radioisotope with a Si(Li) detector. A reasonable agreement is found between the present experimental results and the theoretically calculated values based on photoionization cross sections by Scofield using Hartree-Slater and Hartree-Fock central potential theory.

Kα and Kβ X-ray fluorescence cross-sections in the atomic region 26⩽ Z⩽42 excited by 59.5 keV photons

The Kα and Kβ X-ray fluorescence (XRF) cross-sections were experimentally determined for elements in the range 26⩽ Z⩽42. The obtained experimental results were in good agreement with the theoretical values.

Calculation of average M shell fluorescence yields for elements with 29 ≤Z ≤ 100

Average M shell fluorescence yields ( wM) and the total M shell x-ray fluorescence (MXRF) cross-sections (s x) at 6 keV were calculated theoretically for elements with 29 £ Z £ 100. These calculated values were compared with other experimental and theoretical values. Copyright ” 1999 John Wiley & Sons, Ltd.

Chemical effects on L X-ray fluorescence cross-sections of Ba, La, and Ce compounds

Abstract Chemical effects on the photon induced L X-ray fluorescence cross-sections ( σ L α , σ L β and σ L γ ) for Ba, La and Ce compounds were investigated. The samples were excited by gamma rays with energy 59.5 keV from an Am 241 radioisotope source. L X-rays emitted by samples were counted by a Si(Li) detector with resolution 160 eV at 5.9 keV. We observed chemical effects on the photon-induced L X-ray fluorescence cross-sections ( σ L α , σ L β and σ L γ ) for Ba, La and Ce compounds. Our values were compared with the calculated theoretical values.

L X-ray fluorescence cross-sections of heavy elements excited by 16.04, 16.90 and 17.78 keV photons

Abstract L l , L α , L β , L γ X-ray fluorescence cross sections have been measured for the elements Au, Pt, W, Lu, Yb, Tm, Ho, Dy and Tb using photon energies of 16.04, 16.90 and 17.78 keV. Measurements have been performed using an X-ray tube with a secondary-exciter system as an excitation source. The secondary exciters used are Zr, Nb and Mo of pure metal sheets (99.99%). A Mo X-ray tube with a secondary-target arrangement was used to obtain high intensity with a high degree of monochromaticity. Using an X-ray tube made it possible to measure X-ray fluorescence cross-sections and intensity ratios even for low intensity X-ray lines. The experimental values of the cross-sections were determined by measuring the absolute yield of L subshell X-rays emitted from a standard target of a given element irradiated with photons of given energy. The theoretical values of the cross-sections were calculated using theoretically tabulated values of subshell photoionization cross-sections, fluorescence yields, Coster–Kronig transition probabilities and radiative decay rates. Experimental results have been compared with the theoretically calculated values of L X-ray cross-sections. A fairly good agreement is observed between the experimental and the calculated values. The intensity ratios I Lβ / I Lα and I Lγ / I Lα were measured and found to be in good agreement with the calculated values.

Measurement of L subshell X-ray fluorescence cross sections and L subshell fluorescence yields for elements in the atomic range 73≤Z≤92 at 60 keV

L i (i=1, 2 and 3) X-ray fluorescence cross sections have been measured for ten elements in the atomic range 73≤Z≤92 at 60 keV. The values of L i subshell fluorescence yields (ω1, ω2 and ω3) have been measured for the same elements using the presently measured cross section values and the theoretical L i subhell photoionisation cross sections, Coster-Kronig transition probabilities and emission rates. The measured X-ray fluorescence (XRF) cross section values are in general agreement with the theoretical values evaluated using L subshell fluorescence yields, Coster-Kronig transition probabilities, emission rates and subshell photoionisation cross sections. Furthermore, the values of L subshell fluorescence yields are in good agreement with the theoretical values.

K-shell X-ray Fluorescence Cross-sections and YieldsMeasurements in 12 Elements from Zr to Yb at 122 keV

K x-rays for the elements Zr, Mo, Ag, Sn, Cs, Ba, Ce, Nd, Gd, Dy,Er and Yb were measured following ionization by 122 keV γ-raysfrom a 57Co annular source. From these measurements K-shellfluorescence cross-sections were calculated and K-shell fluorescenceyields were extracted from present experimental cross-sections withtheoretical K-shell photoionization cross-sections. The obtainedresults for x-ray fluorescence cross-sections are compared with thetheoretical estimates based on relativisticDirac–Hartree–Slater theory. Measurement of K x-rayfluorescence yields for these elements are compared theoreticalpredictions, literature experimental values and semiempiricalfits.

Alloying Effect on K X-Ray Fluorescence Cross-Section in CrxNi1-xand CrxAl1-xAlloys

Alloying Effect on K X-Ray Fluorescence Cross-Section in Cr_xNi_1-xand Cr_xAl_1-xAlloys

Measurement of LI, Lα, Lβ and Lγ x-ray fluorescence cross-sections in heavy elements excited by 59.5 and 123.6 keV photons

L1, Lα, Lβ and Lγ XRF cross-sections were measured in heavy elements 73 ⩽ Z ⩽ 92 at excitation energies of 59.5 and 123.6 keV photons. Measurements were made using two excitation sources. 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. It is observed that the measured L XRF cross-section values for the elements are in general agreement with the theoretical ones evaluated using L-subshell fluorescent yields (ωi) and Coster-Kronig transition probabilities (fij) based on the relativistic Dirac-Hartree-Slater theory. The present and previous measured and calculated values of the cross-sections are tabulated to bring out the existing status of L x-rays production cross-sections.

Chemical effect on L X-ray fluorescence cross-sections of Hg, Pb and Bi compounds

Chemical effect on the photon induced L X-ray fluorescence cross-sections ( σ L α , σ L β and σ L γ ) for Hg, Pb and Bi compounds were investigated. The samples were excited by gamma rays with energy 59.5 keV from 241Am radioisotope source. L X-rays emitted by samples were counted by a Si(Li) detector with resolution 160 eV at 5.9 keV. We observed chemical effect on the photon induced L X-ray fluorescence cross-sections ( σ L α , σ L β and σ L γ ) for Hg, Pb and Bi compounds. Our values were compared with calculated theoretical values.

Elastic scattering of 22.1-keV photons by elements in the atomic region 12⩽Z⩽92

Differential cross sections for the elastic scattering of 22.1-keV photons by 30 elements in the atomic region 12\ensuremath{\leqslant}Z\ensuremath{\leqslant}92 have been measured at an angle of 117\ifmmode^\circ\else\textdegree\fi{}. The measurements were performed under vacuum using Si(Li) detector and $^{109}\mathrm{Cd}$ radioisotope as photon source. The intensity of incident photons, detector efficiency, and other geometrical factors was determined by measuring the K x-ray yields from targets of various elements with 30\ensuremath{\leqslant}Z\ensuremath{\leqslant}52 excited by photons from $^{109}\mathrm{Cd}$ and $^{241}\mathrm{Am}$ radioactive sources and from the knowledge of K x-ray fluorescence cross sections. The present measured elastic scattering cross sections have been compared with those obtained in the independent-particle approximation through calculations of modified-relativistic form factors (MF's), a combination of MFs and angle-independent 'anomalous' scattering factors (ASF's), and the relativistic second-order S matrix. The MF values are found to be enormously larger than the measured ones in case of elements with K-shell or ${\mathrm{L}}_{1}$-subshell binding energy in the vicinity of 22.1-keV incident photon energy, and exhibit general agreement for other elements. The MF values in combination with ASF's and the S-matrix values are found to be on an average higher by 9% and 12%, respectively, than the measured values. These deviations increase up to 20% in case of elements with K-shell or ${\mathrm{L}}_{1}$-subshell binding energy just below the incident photon energy, and further decrease to \ensuremath{\sim}5% in case of elements with K-shell binding energy above the incident photon energy. The measured values for Al and Mg having electron binding energies far away from the incident photon energy show good agreement with different calculations.

Choice Between the Use of Experimental and Theoretical Values of L Subshell X-Ray Fluorescence Cross-Sections for Various Applications

L x-ray fluorescence cross-sections in Au, Pb, Th and U at K conversion x-rays of Cd and In were measured using three different experimental arrangements. In contrast to the findings of Rao et al. that the measured values are consistently higher than the calculated values by 20-25%, the present results do not show any regular systematic trends indicating any departure from theory. The deficiencies in their method of measurement are pointed out and the plausible reasons for the discrepancy that they reported are discussed.

Choice Between the Use of Experimental and Theoretical Values of L Subshell XRay Fluorescence CrossSections for Various Applications

L x-ray fluorescence cross-sections in Au, Pb, Th and U at K conversion x-rays of Cd and In were measured using three different experimental arrangements. In contrast to the findings of Rao et al. that the measured values are consistently higher than the calculated values by 20–25%, the present results do not show any regular systematic trends indicating any departure from theory. The deficiencies in their method of measurement are pointed out and the plausible reasons for the discrepancy that they reported are discussed.

Measurement of total and photoelectric cross sections of rare earth elements present in compounds for 123.6 keV and 145.4 keV photons

A new, simple and direct method proposed earlier by us has been employed here to measure the total photoelectric cross section of rare earth elements in the range 58 ⩽ Z ⩽ 66 present in compounds at 123.6 keV and 145.4 keV photon energies. The K X-ray fluorescence intensities emitted by these elements, from irradiating their compounds by the photons of above energies, are measured using a NaI (Tl) spectrometer system in a 2π geometrical configuration. The K X-ray fluorescence cross sections of the rare earth elements are determined, from which the total photoelectric cross sections are evaluated. Total mass attenuation coefficients of compounds for the K X-ray and the incident radiations respectively have been measured and these values were compared with the corresponding theoretical values and a good agreement between them is obtained.

L X-ray fluorescence cross sections in the atomic region 59 ≤ Z ≤ 82 excited by 16.58 keV photons

LL, Lα, Lβ, and Lγ X-ray fluorescence cross sections for Pr, Sm, Gd, Dy, Ho, Er, Yb, Pt Au, and Pb were measured at the excitation energy 16.58 keV. An X-ray tube and a secondary excitor system was used instead of radioisotopes for the measurements. Experimental cross sections are compared with the theoretical estimates based on relativistic Dirac–Hartree–Slater theory. Average L-shell fluorescence yields [Formula: see text] are deduced using the present experimental cross sections and the theoretical subshell photoionization cross sections. The derived average fluorescence yields are fitted by least squares to polynomials in Z of the form ΣnanZn and compared with theoretical and earlier fitted values. Good agreement is observed ' between the experimental results and the theoretical estimates based on relativistic Dirac–Hartree–Slater theory.

L X-ray fluorescence cross sections and yields for mediumZ elements in the energy region 5.47 ≤E ≤ 9.36 keV

TotalL X-ray fluorescence cross sections have been measured in the atomic region 39 ≤Z ≤ 51 excited by 5.47, 6.47, 7.04, 7.57, 8.14, 8.74 and 9.36 keV photons. Experimental cross sections are compared with the theoretical estimates of Chen et al. based on relativistic Dirac-Hartree-Slater theory. Good agreement is observed between experimental results and theoretical estimates in the studied atomic and energy region. Experimental fluorescence yields have been evaluated using the experimental fluorescence cross sections and theoretical subshell photoionization cross sections. Fluorescence yields are fitted by least squares to fifth-order polynomials inZ of the form Σnanzn and compared with theoretical and earlier fitted values. The deviation of the average fluorescence yield in the atomic region 46Z 51 with new theoretical estimates of\(\bar \omega _L \), calculated using the ECPSSR (Energy loss Coulomb deflection Perturbed Stationary State Relativistic effects) theory of Brandt and Lapicki and the fitted values clearly indicate the weak dependence of the average fluorescence yield on the initial vacancy distribution.

L X-ray fluorescence cross sections and yields for medium Z elements in the energy region 5.47≤ E ≤9.36 keV

L X-ray fluorescence cross sections and yields for medium Z elements in the energy region 5.47≤ E ≤9.36 keV

Ll, Lα, Lβ and Lγ X-Ray Fluorescence Cross-sections for Ce, Pr and Sm Excited by Y and Mo Kα X-Ray Photons

Ll, Lα, Lβ and Lγ x-ray fluorescence cross-sections were measured for Ce, Pr and Sm at excitation energies of 14.94 and 17.44 keV using a low-energy Si(Li) detector coupled to a model 1024 computerized multi-channel analyser. Experimental results are compared with the theoretical estimates of Chen et al. based on relativistic Dirac-Hartree-Slater theory. Good agreement was observed between the experimental and theoretical values.