X-ray Fluorescence Cross-sections Research Articles

L-series X-ray fluorescence cross section measurements for 72Hf employing synchrotron radiation

In the present work, the Hf target was irradiated by tuning the energy (Ep) of synchrotron radiation across the Li (i = 1–3) edge-energies ranging from 9.6 keV to 14.0 keV in order to measure the cross sections for production of the fluorescent Lk X-rays (k = l, α, η, β1,6, β3, β4, β2,15, β5,7, β9,10, γ1,5, γ2,3,6,8, γ4). These measurements were performed with the aim to check the validity of independent particle approximation (IPA) models at incident photon energies in proximity to the Li absorption edges of a heavy transition element. The measured cross sections were compared with three sets of values calculated using the X-ray emission rates based on the Dirac-Fock model, the Li (i = 1–3) sub-shell photoionization cross-sections based on the non-relativistic Hartree-Fock-Slater model and three sets of the fluorescence (ωi) and Coster-Kronig (fji) yields.

Experimental measurements of X-rays emission cross sections induced by photons

Abstract The energy-dispersive X-ray fluorescence (ED-XRF) technique has been used for measurements of K α , K β , and total K X-rays emission cross sections induced by photons, as well as K-shell fluorescence yields for pure elements with 22 ⩽ Z ⩽ 49. These metals have been irradiated at 59.54 KeV excitation energy from an 241Am annular radioactive source. The characteristic K X-rays emitted by the targets have been detected with a Silicon drift detector (SDD); the net areas of the K α and K β spectral peaks have been determined using the fitting process of PYMCA software. The obtained experimental values of the K X-ray fluorescence cross sections and the K-shell fluorescence yields were compared to the theoretical calculated ones and also to the experimental results obtained from a different experimental setup using a point source. The obtained values were between (6.84 ± 0.55 b/at.) and (891.0 ± 67.5 b/at.) for pure metals form Scandium to Indium. Experimental values were in good agreement with theoretical values within limits of uncertainty, as well as with the data reported in the literature. Moreover, the experimental determination of K X-ray fluorescence cross-section of scandium (Sc) at 59.54 KeV has not been preceded as far as we know. The value obtained is (6.84 ± 0.55 b/at). This new result obtained maybe contribute to the enrichment of the available databases.

K shell fluorescence parameters of some elements at 59.54 keV: Experimental and theoretical results

Kα, Kβ and total K X-ray fluorescence cross-sections, K shell fluorescence yields, Kβ/Kα X-ray intensity ratios, K shell level widths, K shell life times, K to L shell vacancy transfer probabilities, K shell jump ratios, Auger electrons emission ratios and excitation factors for some elements in the atomic number range 22 ≤ Z ≤ 48 have been investigated. A Si(Li) detector and Am-241 annular radioactive source were used in the measurements. The obtained experimental data were crosschecked with theoretically calculated results and other available experimental results from the literature. It was observed that there is a good agreement between them within experimental uncertainties.

Determination of L X-ray fluorescence cross-sections in the atomic range of elements 57 ≤ Z ≤ 69 in an external magnetic field

• No data is available about the L X-ray fluorescence cross sections for lantanide elements an external magnetic field in the literature. • The L X-ray fluorescence cross sections are calculated for lanthanides without magnetic field and at external magnetic field. • The experimental results are agreed with the theoretical predictions without magnetic field. • This study may be important interms of understanding interaction between magnetic field and matter. L X-ray fluorescence cross sections have been determined for La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er and Tm elements at the magnetic field ( B = 0.8 Tesla) and without magnetic field with energy dispersive X-ray fluorescence spectroscopy (EDXRF) technique. The fluorescence spectra were obtained by using Si(Li) solid-state detector with a high resolution and 241Am radioactive point source (with 59.5 keV γ-rays). The results have been compared with the theoretical results without the magnetic field. It has been observed a good agreement between the experimental and the theoretical results and that L X-ray fluorescence cross sections of Lanthanide elements change with the magnetic field except σ Ll of Gd, σ Lβ of Dy and σ Lγ of Ce and Tm.

Measurement of M subshell X-ray fluorescence parameters of gold, lead and bismuth using 7 keV synchrotron radiation

The Mα and Mβ X-ray fluorescence cross sections, IMα/IMβ intensity ratio, M5 subshell fluorescence yield and M5 subshell Auger yield for gold, lead and bismuth elements were determined using Indus-2 synchrotron radiation available at the Raja Ramanna Center for Advanced Technology, India. A 7 keV synchrotron radiation was used to generate the characteristic M X-ray photons in gold, lead and bismuth and consequent X-ray photons were detected with Amptek silicon drift detector which has energy resolution of 129 eV at 5.9 keV. By measuring the area under Mα and Mβ X-ray peaks, Mα and Mβ X-ray fluorescence cross sections, IMα/IMβ intensity ratio, M5 subshell fluorescence yield and M5 subshell Auger yield were determined for gold, lead and bismuth. Experimentally determined values were compared with the theoretical and other experimental values available in the literature.

Variation of Coster-Kronig enhancement factors at different excitation energies of the elements in the atomic number range 41 ≤ Z ≤ 49

In this study, L X-ray fluorescence (XRF) cross-sections of elements with atomic number 41 ≤ Z ≤ 49 were theoretically calculated according to different excitation energies. Also, the Coster-Kronig (CK) enhancement factors observed as a result of the effect of non-irradiated Coster-Kronig transitions on L X-ray fluorescence cross-sections were theoretically calculated at different excitation energies. The change of both L XRF fluorescence cross-sections and the Coster- Kronig enhancement factors against energy were examined. The results obtained were compared with the values ​​in the literature.

Chemical effect on K shell X-ray fluorescence parameters for some Mn and Ni compounds

Kα, Kβ and total K X-ray fluorescence cross-sections, K shell fluorescence yields, Kβ/KαX-ray intensity ratios, K to L shell vacancy transfer probabilities and Auger electrons emission ratios of some selected Mn and Ni compounds have been investigated. The measurements were carried out by using Am-241 radioactive source and high-resolution Si(Li) detector. The measured results were compared with other experimental values and theoretical calculations. Our values are in good concordance with calculated theoretical and other experimental values.

Effect of annealing temperature on K-shell X-ray fluorescence parameters of zinc oxide thin films prepared by the sol-gel method

Zinc oxide thin films were grown on a glass substrate by a sol-gel process using a spin-coating technique. The obtained thin films were annealed between 350 °C and 550 °C in 50 °C steps and were then characterized using X-ray diffraction, scanning electron microscopy, and X-ray fluorescence techniques. The samples were stimulated by 59.5 keV gamma rays emitted from an Americium-241 annular radioisotope source. K X-rays emitted by samples were counted using an ultra-low energy germanium detector with a resolution of 150 eV at 5.96 keV. It was found that there was generally a decrease in both the Kβ/Kα X-ray intensity ratios and the K X-ray fluorescence cross sections for zinc oxide between 350 °C and 500 °C, but not at 550 °C. In addition, the X-ray diffraction patterns of the films showed that the transition phase from an amorphous to a polycrystalline hexagonal wurtzite structure was complete at an annealing temperature of 500 °C. The results show that variations in these parameters can be explained by the reorganization of atoms and the charge transfer process due to the effect of the annealing temperature on the elements forming the compounds.

L X-ray fluorescence cross-sections measurements for elements Ba, La and Ce at synchrotron radiation energies 7, 8, 9 and 10 keV

Ll, Lα, Lβ and Lγ1 X-ray fluorescence cross-sections have been measured for the elements Ba, La and Ce at 7, 8, 9 and 10 keV synchrotron radiations. A Peltier cooled Vortex solid state detector (SII Nano Technology, USA) with an energy resolution of 138 eV at 5.96 keV X-rays was employed for the analysis. The experimental results were compared with the theoretical values estimated from the data of Puri et al. (1993) and Campbell (2003). Two different models Dirac-Hartree-Slater (DHS) and Dirac-Fock (DF) were used to compare the theoretical and experimental results. Most of the experimental measurements were found in good agreement with the theoretical values of Puri et al. (1993) based on DF model.

Measurement of L XRF cross sections for elements with 33 ≤ Z ≤ 51 and their interpretation in terms of L (i = 1–3) subshell vacancy decay parameters

Abstract The Li (i = 1–3) subshell integral X-ray fluorescence (XRF) cross sections have been measured for 17 elements with 33 ≤ Z ≤ 51 following photoionization by the Mn K X-rays (EKαβ = 5.96 keV). The Li (i = 1–3) subshell X-rays were measured using a low-energy Ge (LEGe) detector at an emission angle, ψ = 125°, where angle-dependent emission effects, if any, are nullified as P2(cos ψ) ∼ 0. The XRF cross sections were interpreted in terms of available sets of theoretical Li (i = 1–3) subshell photoionization cross sections, radiative transition probabilities, and the atomic vacancy decay parameters, namely, fluorescence (ωi) and Coster-Kronig (fij) yields. A set of L1 subshell fluorescence (ω1) yields was deduced for the elements with 37 ≤ Z ≤ 51 from the present measured Lγ2,3,(4) [L1-N2,3(O2,3)] XRF cross sections. The ω1 values exhibit jumps at Z = 40 and 49, which are identified to be due to cut-off of the L1L2M4,5 and L1L3M4,5 Coster-Kronig (CK) transitions predicted by calculations based on relativistic Dirac-Hartree-Slater (RDHS) model. However, the measured ω1 values are found to differ considerably from those based on the RDHS model calculations for the elements below Z = 50. The pronounced discrepancies between measured and theoretical ω1 values are likely to be due to overestimation of the L1-L2,3M4,5 CK transition rates by a factor of ∼2–3. Our experiential results demand consideration of extra-atomic relaxation from the solid-state effects and exchange splitting in many-body theoretical calculations of the low-energy CK transitions.

Inner shell alignment of atoms in photon impact ionization

The ionization of an atom can result in alignment of the residual ion. In the present work alignment studies are made for some of the high Z elements using different approaches. The theoretical values of the alignment parameter (A2) have been calculated by using the non-relativistic dipole approximation in a point Coulomb potential and analytical perturbation theory in a screened Coulomb potential. Empirical alignment evaluations are done by interpolating experimental L x-ray fluorescence cross-sections along with radiative decay rates. The alignment results are further compared with available theoretical and experimental measurements.

Alloying effect on K shell X-ray fluorescence cross-sections and yields in Ti-Ni based shape memory alloys

K shell X-ray fluorescence cross-sections (σKα, σKβ and σK), and K shell fluorescence yields (ωK) of Ti, Ni both in pure metals and in different alloy compositions (TixNi1-x; x = 0.3, 0.4, 0.5, 0.6, 0.7) were measured by using energy dispersive X-ray fluorescence (EDXRF) technique. The samples were excited by 22.69 keV X-rays from a 10 mCi Cd-109 radioactive point source and K X rays emitted by samples were counted by a high resolution Si(Li) solid-state detector coupled to a 4 K multichannel analyzer (MCA). The alloying effects on the X-ray fluorescence (XRF) parameters of Ti-Ni shape memory alloys (SMAs) were investigated. It is clearly observed that alloying effect causes to change in K shell XRF parameter values in Ti-Ni based SMAs for different compositions of x. Also, the present investigation makes it possible to perform reliable interpretation of experimental σKα, σKβ and ωK values for Ti and Ni in SMAs and can also provide quantitative information about the changes of K shell X-ray fluorescence cross sections and fluorescence yields of these metals with alloy composition.

Measurements of K X-ray fluorescence cross-sections, fluorescence yields, level widths and radiative vacancy transition probabilities for the elements Zr, Mo, Cd, Er at 59.54 keV

K shell X ray fluorescence cross sections, fluorescence yields, level widths and radiative vacancy transition probabilities were investigated for the elements Zr, Mo, Cd, Er. The measurements were performed using photons of 59.54 keV emitted from an Am-241 (about 100 mCi) point source and a high resolution Si(Li) detector. The experimental results were compared with theoretical calculations and the other results obtained from literature.

M sub-shell X-ray fluorescence cross-section measurements for six elements in the range Z = 78–92 at tuned synchrotron photon energies 5, 7 and 9 keV.

M sub-shell X-ray fluorescence cross-sections of elements Pt, Au, Hg, Pb, Th and U have been measured with linearly polarized photon beams from Indus-II synchrotron source at Raja Ramanna Centre for Advanced Technology (RRCAT), India at tuned 5, 7 and 9 keV energies less than the L3 edge energy of elements. Measurements at present energies and elements are not available in literature. Therefore, measured cross-sections for Mξ, Mδ, Mα, Mβ, Mγ, Mm1 and Mm2 group of X-rays were compared with calculated theoretical values based upon Non Relativistic Hartree–Slater (NRHS) and relativistic Dirac-Fork (DF) and Dirac–Hartree–Slater (DHS) models. The measured cross-sections along with our earlier quoted measurements at 8 and 10 keV by Kaur et al. [Nucl. Instrum. Meth. B, 2014; 320: 37] are found in good agreement with DF and DHS values around 20% deviations and are highly deviated from NRHS values. Most of the spots of observed high deviations in measured and theoretical cross-sections are found to coincide with the presence of crisscrosses/sharp variations in contributing physical parameters photo-ionization cross-sections σMi’s and Coster–Kronig yields fij’s with Zs.

Rayleigh scattering of 66Dy-K X-rays in elements with 22 ≤ Z ≤ 90

Rayleigh scattering differential cross sections for the 45.2keV (66Dy Kα2), 46.0keV (66Dy Kα1) and 52.1keV (66Dy Kβ1,3) X-rays have been measured at 139° in 44 elements with 22 ≤ Z ≤ 90. The measurements were performed using a radiation source consisting of an annular 66Dy foil excited by the 59.54keV γ-ray photons from 241Am radioactive source. Intensity of the incident photons along with other geometrical factors were determined by measuring the isotropically emitted K X-ray yields from targets and knowledge of the corresponding K X-ray fluorescence cross sections. The measured Rayleigh scattering cross sections are compared with those based on various form factor formalisms and the state-of-the-art S-matrix calculations to differentiate between their relative efficacies. The scattering cross sections based on the modified form factor (MF) formalism exhibit large deviations for the elements with electron binding energies in vicinity of the incident photon energy, and these deviations smooth out on inclusion of the anomalous scattering factors (ASFs) to the MF values. The cross sections based on the MF after including ASF's are found to be on an average higher by ~ 8% as compared to the measured ones. The S-matrix values exhibit in general good agreement with the measured cross sections for the elements with 22 ≤ Z ≤ 90.

Measurement of large angle Rayleigh scattering cross sections for 39.5, 40.1 and 45.4 keV photons in elements with 26 ≤ Z ≤ 83

The present work reports Rayleigh scattering cross section measurements for the 39.5keV (Sm- Kα2), 40.1keV (Sm-Kα1) and 45.4keV (Sm-Kβ1,3) X-ray photons in 35 elements with 26 ≤ Z ≤ 83 at backward angle of 139°. The scattering measurements were performed in reflection mode geometrical set up involving a secondary photon source consisting of Samarium (62Sm) target excited by the 59.54keV γ-rays from the 241Am radioactive source. The scattered photons were detected using a low energy germanium (LEGe) detector. The product of detector efficiency, intensity of incident photons and other geometrical factors were determined by measuring the K X-ray yields from targets with 47 ≤ Z ≤ 59 and knowledge of the respective K X-ray fluorescence cross sections. The measured cross sections are compared with the theoretical cross sections based on the modified form factor (MF) formalisms and the second-order S-matrix approach. The experimental results demonstrate large deviations from the MF values for the elements with K shell binding energy (BK) in vicinity of the incident photon energy (Ein), which smooth out with inclusion of the anomalous scattering factors (ASFs). The S-matrix values, in general, agree with the measured cross sections for all the elements under investigation.

L sub-shell fluorescence cross-section measurements for elements, Z = 62–67, at tuned photon energies

L sub-shell X-ray fluorescence (XRF) cross-sections for 6 elements with Z= 62-67 have been measured at tuned photon energies on synchrotron Beamline-16, Indus-2, RRCAT, India. Three incident photon energies at the intervals of 0.1keV were tuned in each region; > EL1, < EL1 & >EL2 and <EL2 & >EL3 where ELi are Li (i= 1-3) absorption edge energies of element. No single measurement is available in literature for present incident photon energies and elements, therefore, certainty and reliability of the measurements have been judged from three different aspects. One, from comparison of measured cross-sections with calculated theoretical values. Second, evaluation of Coster-Kronig yield (fij’s) and fluorescence yield (ωi’s) fine parameters from measured XRF cross-sections with formulations derived from total intensity of X-rays originating from individual sub-shells that generated a data set for fij’s and ωi’s of six elements for comparison with available theoretical/empirical/experimental values. Third, from trends of total measured L XRF cross-sections with photon energy for the elements. The results were found affected by the 4f electron filling in the elements.

Alloying effect on K shell X-ray fluorescence cross-sections and intensity ratios of Cu and Sn in Cu1Sn1−x alloys using the 59.5 keV gamma rays

Kβ/Kα, intensity ratios and σKα,β production cross-sections of Cu and Sn were measured in pure metals and in different alloys which have different compositions (CuxSn1−x x=0.48, 0.41, 0.14 and 0.06). The samples were excited by 59.5keV γ-rays from 241Am annular radioactive source. K X-rays emitted by samples were counted by an Ultra-LEGe detector with a resolution of 150eV at 5.9keV. Comparison of the σKβ production cross-sections and Kβ/Kα X-ray intensity ratio values for Cu and Sn with the theoretical and semi-empirical calculations indicates that they are in the inverse direction with concentration of constituent element in the alloys. The results show that variations in these parameters can be explained with the charge transfer process between the elements which constitute the alloys.

Calculations of photo-induced X-ray production cross-sections in the energy range 1–150 keV and average fluorescence yields for Zn, Cd and Hg

In this paper, we calculate the K-, L- and M-shells X-ray production, and X-ray fluorescence cross-sections after photo-induced ionization, for Zn, Cd, and Hg, and for incident photon energy range from 1 to 150 keV. For this purpose, the corresponding average fluorescence yields for Zn, Cd, and Hg as well as the photoionization cross-sections were calculated using the Dirac–Fock method. Subshell fluorescence, intrashell and intershell yields are obtained consistently from radiative and radiationless transitions calculated in the exact same method. A comprehensive account of the relations between the X-ray production, X-ray fluorescence cross-sections and the photoionization cross-sections and these yields is presented. Comparisons are made with results from other authors. The obtained values for the photoionization cross-sections are in good agreement with the widely used data of Scofield in the studied energy range. However our results for the X-ray fluorescence cross sections seem to favor some data relatively to others. The energy dependence of the average fluorescence yields is discussed, in particular, the reliability of extrapolated data for lighter elements from measurements and calculations in heavier elements above the inner shell absorption edges is questioned. Tabulated data on photoionization and X-ray production cross-sections are presented for the incident photon energy range 1–150 keV in steps of 1 keV.

M sub-shell X-ray fluorescence cross-section measurements in high Z elements with X-ray tube photon source

X-ray tube has been used for selective M sub-shell excitations in a single reflection set-up for Pt, Au, Pb, Th and U required for M sub-shell fluorescence cross-sections measurements. Weighted photon energy and total intensity of the incident flux between E M5 edge and tube anode voltage were evaluated following a specific procedure. Comparison of measured cross-sections with the calculated ones from existing DHS/DF model based theoretical data on atomic parameters lend support to the present findings.