K-shell Fluorescence Yield Research Articles

Experimental determination of the sulfur K-shell fundamental parameters employing the holistic approach

Abstract Sulfur and its compounds are both very abundant in the environment and very important for technological applications such as batteries. X-ray spectroscopic characterizations of sulfur compounds for a quantitative determination of the present amount of sulfur often requires a good knowledge on the atomic fundamental parameters involved. These quantitatively describe the processes of photoionization and X-ray fluorescence emission, making them crucial for X-ray spectroscopy-based quantifications. 
By employing the recently demonstrated holistic approach, the atomic fundamental parameters of the sulfur K-shell were experimentally determined using the radiometrically calibrated instrumentation of the Physikalisch-Technische Bundesanstalt (PTB). The transition probabilities of the main K-shell fluorescence lines, the K-shell fluorescence yield, the K-shell Auger yield, the subshell photoionization cross section and fluorescence production cross section were determined by means of photon energy dependent X-ray fluorescence and transmission measurements on a thin InS coated silicon nitride membrane. The results are also downloadable from Zenodo as plain text.

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- and L-shell theoretical fluorescence yields for the Fe isonuclear sequence

In this work, we present K- and L- shell fluorescence yield values of the full isonuclear sequence of Fe ions, using a state-of-the-art multiconfiguration Dirac–Fock approach. These results may be of importance for spectral fitting and plasma modeling, both in laboratory and astrophysical studies, where Fe is an important benchmark element. The K-shell fluorescence yields were found to be very similar up to the removal of 14 electrons.

Experimental and theoretical approaches for determining the K-shell fluorescence yield of carbon

The knowledge of atomic fundamental parameters, such as the fluorescence yields with low uncertainties, is of decisive importance in elemental quantification involving X-ray fluorescence analysis techniques. However, especially for the low-Z elements, the available data in the literature is either of poor quality, of unknown or very large uncertainty, or both. For this reason, the K-shell fluorescence yield of carbon was determined in the PTB laboratory at the synchrotron radiation facility BESSY II. In addition, theoretical calculations of the same parameter were performed using the multiconfiguration Dirac–Fock method, including relativistic and quantum electrodynamics (QED) corrections. Both values obtained in this work are compared to the corresponding available published data.

High energy PIXE: New experimental K-shell ionization cross sections for silver and gold and comparison with theoretical values from ECPSSR/RECPSSR models

In high energy PIXE, a high energy ion beam, up to several tens of MeV, is used to analyze heavy elements in a thick sample. The knowledge of the interaction cross-section with the atoms is essential to perform quantitative analysis. As measured data in this range of energy are scarce, an experimental campaign was conducted at the C70 cyclotron of the GIP ARRONAX to measure the K-X-ray production cross-sections for silver and gold with proton energies 30, 42, 54 and 68 MeV. The detector efficiency, the beam intensity, and the target thickness were measured accurately to produce precise data. To convert the K-X-ray production cross-sections into the K-shell ionization cross-sections, an average value of the K-shell fluorescence yield, calculated from a compilation of existing data, was used. The outcomes of the campaign are in good agreement with the few existing data and the theoretical prediction of the RECPSSR model.

Characteristic X-ray yields and cross sections of thick targets of Al, Ti, Zr, W and Au induced by keV-electron impact

In this paper, pure thick Al (Z = 13), Ti (Z = 22), Zr (Z = 40), W (Z = 74) and Au (Z = 79) targets are bombarded by electrons in an energy range of 5–27 keV, and the experimental thick-target characteristic X-ray yields of K-shell and L-shell, the X-ray production cross sections and the ionization cross sections of inner shells are presented. The present experimental setup and data processing are improved, specifically, a deflection magnet is installed in front of the X-ray detector to prevent the backscattered electron from entering into the X-ray detector, and the bremsstrahlung background spectra calculated from PENELOPE Monte Carlo simulations are used to deduce the net peak areas. The X-ray detector used in this experiment is the XR-100SDD manufactured by Amptek Inc. with a 25 mm<sup>2</sup> C2 ultra-thin window which can detect the low-energy x-rays down to boron Kα line (0.183 keV). Standard sources (<sup>55</sup>Fe, <sup>57</sup>Co, <sup>137</sup>Cs and <sup>241</sup>Am) with an activity accuracy range of 1%–3% (<i>k</i> = 2), supplied by the Physikalisch-Technische Bundesanstalt, Germany (PTB), are used to perform the detector’s efficiency calibration, and in a low-energy range (< 3.3 keV) the efficiency calibration is accomplished by measuring characteristic X-ray spectra produced by 20 keV electron impacting various thickness solid targets (i.e. by the characteristic peak method). The uncertainty of the detector’s efficiency calibration obtained in this paper is ~1.6%. The experimental thick-target characteristic X-ray yield data with an uncertainty of 1.7%–6.2% are compared with the PENELOPE Monte Carlo simulations, in which the inner-shell ionization cross sections are based on the distorted-wave Born approximation (DWBA) calculations, and they are in good agreement with a difference of less than or ~10%. According to the measured thick-target characteristic x-ray yields, the K-shell ionization cross sections for Al, Ti and Zr and the L-shell X-ray production cross sections for Zr, W and Au are also obtained with an uncertainty of 5%–8% (except for Al due to large K-shell fluorescence yield uncertainty), the difference between the experimental and theoretical data is also less than or ~10%. Moreover, by comparing the thick-target characteristic X-ray yields obtained from the analytical model and the PENELOPE Monte Carlo simulations at the electrons’ incident angles of 45° and 90°, it is found that the degree of agreement between the results from the analytical model and the Monte Carlo simulations at the incident angle of 90° is better than at the incident angle of 45°. Moreover, the contributions of the secondary electrons and bremsstrahlung photons to the characteristic X-ray yield are also given based on the PENELOPE Monte Carlo simulations. As for the elements studied in this paper, for the low ionization threshold energy, the contribution of the secondary electrons is ~2%, and however, for the high ionization threshold energy, the contribution is ~10%–20%. These contributions depend weakly on the energy of the incident electrons and show that these contributions are closely correlated with atomic number.

Experimental determination of the x-ray atomic fundamental parameters of nickel

The x-ray atomic properties of nickel (Ni) were investigated in a unique approach combining different experimental techniques to obtain new, useful and reliable values of atomic fundamental parameters for x-ray spectrometric purposes and for comparison with theoretical predictions. We determined the mass attenuation coefficients in an energy range covering the L- and K-absorption edges, the K-shell fluorescence yield and the and transition probability ratios. The obtained line profiles and linewidths of the and transitions in Ni can be considered as the contribution of the satellite lines arising from the [KM] shake processes suggested by Deutsch et al (1995 Phys. Rev. A 51 283) and Ito et al (2016 Phys. Rev. A 94 042506). Comparison of the new data with several databases showed good agreement, but also discrepancies were found with existing tabulated values.

Experimental determination of the oxygen K-shell fluorescence yield using thin SiO2 and Al2O3 foils

In this work, the K-shell fluorescence yield for oxygen ωO,K−shell is determined experimentally, employing the radiometrically calibrated X-ray fluorescence instrumentation of the Physikalisch-Technische Bundesanstalt (PTB), Germany's National Metrology Institute. Four free-standing thin foils with two different thicknesses of both SiO2 and Al2O3 were used in order to derive an experimental value for this atomic fundamental parameter. Multiple excitation photon energies were applied to record fluorescence spectra of all four samples. The resulting value (ωO,K−shell=0.00688±0.00036) is almost 20 % higher than the commonly used value from the Krause tables [M. Krause, Atomic Radiative and Radiationless Yields for K and L shells, J. Phys. Chem. Ref. Data 8(2), 307–327 (1979)]. In addition, the achieved total uncertainty budget for the new experimental value is reduced significantly in comparison to available literature data. For validation purposes, thin SiO2 layers on Si samples were used. Here, the layer thicknesses derived from X-ray reflectometry are well in line with our X-ray fluorescence quantification results based on the new experimental value for the O K-shell fluorescence yield.

New K-shell fluorescence yields curve for elements with 3 ≤ Z ≤ 99

The measured K-shell fluorescence-yield values reported in the literature from 1934 to 2015 (about 737 new measurements) were used to deduce new empirical K-shell fluorescence yields for elements in the atomic range 3 ≤ Z ≤ 99. In order to deduce the empirical K-shell fluorescence yield, the experimental data were fitted using the quantity (ω K /(1 - ω K ))1/4 with respect to the atomic number Z. The results were compared to other theoretical, semi-empirical and experimental values reported in the literature. Reasonable agreement was obtained between our result and those of other works.

K-shell fluorescence yields and their uncertainties for use in hybrid K-edge densitometry

Hybrid K-edge densitometry (HKED) is a non-destructive analytical assay technique used to provide rapid determination of actinide concentration in tank solutions. Of special interest for HKED is the estimation, along with associated uncertainties, of the ratio of the flouresence yeilds, ωK, of uranium and plutonium. Limited experimental data for ωK(Z) as a function of atomic number, Z, exist and the data are subject to experimental uncertainty. Previous studies have provided values for ωK(Z) with uncertainty estimates but have not included covariance information. We use a phenomenological model with a bootstrapping method to generate the ratio ωK(94)/ωK(92) and associated uncertainty.

Determination of K–L vacancy transfer probabilities of some 3d elements using synchrotron radiation

The K–L total vacancy transfer probabilities (ηKL) of some 3d elements have been determined using Indus-2 synchrotron radiation. The targets, such as Cr, Cu, and Zn, are excited by using 6.5, 10, and 11 keV synchrotron radiation, respectively. The K X-ray photons are detected with a silicon drift detector, which has an energy resolution of 130 eV at 5.9 keV. By measuring the K-shell fluorescence yield and K X-ray intensity ratio, the K–L vacancy transfer probabilities have been determined. Measured values have been compared with the theoretical values and other experimental values.

Vanadium fine-structure K-shell electron impact ionization cross sections for fast-electron diagnostic in laser–solid experiments

The K-shell electron impact ionization (EII) cross section, along with the K-shell fluorescence yield, is one of the key atomic parameters for fast-electron diagnostic in laser–solid experiments through the K-shell emission cross section. In addition, in a campaign dedicated to the modeling of the K lines of astrophysical interest (Palmeri et al. (2012)), the K-shell fluorescence yields for the K-vacancy fine-structure atomic levels of all the vanadium isonuclear ions have been calculated.In this study, the K-shell EII cross sections connecting the ground and the metastable levels of the parent vanadium ions to the daughter ions K-vacancy levels considered in Palmeri et al. (2012) have been determined. The relativistic distorted-wave (DW) approximation implemented in the FAC atomic code has been used for the incident electron kinetic energies up to 20 times the K-shell threshold energies. Moreover, the resulting DW cross sections have been extrapolated at higher energies using the asymptotic behavior of the modified relativistic binary encounter Bethe model (MRBEB) of Guerra et al. (2012) with the density-effect correction proposed by Davies et al. (2013).

Measurements of K -shell X-ray production cross-sections and fluorescence yields for some elements in the atomic number range 28≤ Z ≤40

Abstract K shell X-ray production cross-sections ( σ K α and σ K β ) have been measured for some elements in the atomic number range 28≤Z≤40. Measurements have been carried out at 16.896 keV excitation energy using secondary source. K X-rays emitted by samples have been counted by a Si(Li) detector with 160 eV resolution at 5.9 keV. The values of K-shell fluorescence yields ( ω K ) have been evaluated for the same elements. The results obtained for K X-ray production cross-sections and fluorescence yields have been compared with the theoretically calculated values and other available semiempirical values.

Copper fine-structure K-shell electron impact ionization cross sections for fast-electron diagnostic in laser-solid experiments

The K-shell electron impact ionization (EII) cross section, along with the K-shell fluorescence yield, is one of the key atomic parameters for fast-electron diagnostic in laser-solid experiments through the K-shell emission cross section. In addition, copper is a material that has been often used in those experiments because it has a maximum total K-shell emission yield. Furthermore, in a campaign dedicated to the modeling of the K lines of astrophysical interest (Palmeri et al., 2012), the K-shell fluorescence yields for the K-vacancy fine-structure atomic levels of all the copper isonuclear ions have been calculated.In this study, the K-shell EII cross sections connecting the ground and the metastable levels of the parent copper ions to the daughter ions K-vacancy levels considered in Palmeri et al. (2012) have been determined. The relativistic distorted-wave (DW) approximation implemented in the FAC atomic code has been used for the incident electron kinetic energies up to 10 times the K-shell threshold energies. Moreover, the resulting DW cross sections have been extrapolated at higher energies using the asymptotic form proposed by Davies et al. (2013).

Empirical, Semi-Empirical and Experimental Determination of K X-Ray Fluorescence Parameters of Some Elements in the Atomic Range 21 ≤ Z ≤ 30

In this study, the semi-empirical and empirical calculations of K X-ray intensity ratios, K-shell fluorescence yields, and vacancy transfer probabilities have been performed for 3d transition elements. Also, σKα, σKβ production cross-sections, Kβ/Kα intensity ratios, ωK fluorescence yields, and ηKL vacancy transfer probabilities of 3d transition elements have been measured. The samples were excited by 59.5 keV γ-rays from a 241Am annular radioactive source. K X-rays emitted by samples were counted by an Ultra-LEGe detector with a resolution of 150 eV at 5.9 keV.

The fluorescence parameters of Zr and Sb compounds

The K-shell X-ray intensity ratios, the production cross-sections, the average K-shell fluorescence yields were measured for Zr and Sb elements and their compounds. The samples were excited by 59.5 keV X-rays from a 241 Am annular radioactive source. The K X-rays emitted by the samples were counted by an Ultra-LEGe detector with a resolution of 150 eV at 5.9 keV. The experimental values were compared with the theoretical and other experimental values for pure elements. • The elements Sb and Zr are investigated by using Ultra-LeGe detector. • The fluorescence parameters were calculated both theoretically and experimentally. • The obtained results were compared with theoretical results and the previous studies.

K-shell ionization and radiative electron capture in 0.75–2.5 MeV u−1 32S, 35Cl + Cu atomic collisions

From the measured target thickness dependence of the K x-ray and radiative electron capture (REC) yields in the 0.75–2.5 MeV u−1 32S, 35Cl + Cu collisions, the cross sections for K x-ray production and REC, in dependence on collision energy, have been determined. In comparison with theory, we find simple models that describe rather well some of the present results. The target (Cu) K x-ray production cross sections are in fair agreement with ECPSSR model predictions. The REC theoretical calculations (Stobbe model times 11, the number of loosely bound electrons in Cu) are in agreement with the present data for Cl + Cu collision, but overestimate the data for S + Cu collision by approximately a factor of 2. Large enhancements for the projectile K-shell fluorescence yields, up to 10 for S and 6 for Cl, as well as for K-shell vacancy lifetimes, up to 16 for S and 21 for Cl, are reported.

K-Shell X-Ray Fluorescence Studies of Some Elements in the Atomic Number Range 26 = Z = 70

K-shell fluorescence yields of low, medium Z and rare earth elements were determined using Si(PIN) detector and HPGe detector employing reflection geometry set up. Target atoms were excited using 59.5 keV gamma rays emerging from Am-241 source of strength 300 mCi. Background radiation and multiple scattering effects were minimized by properly shielding the detector. The elemental foils of uniform thickness and 99.9% purity were used in the present investigation. The fluorescent spectra were recorded in an 8K and 16K multi channel analyzer. The data were carefully analyzed and total K-shell fluorescence yields were calculated. The resulting yield values are compared with the available experimental and theoretical values.

Alloying effect on K X-ray intensity ratio and production cross section values of Zn and Cr in ZnCr alloys

In this study, σKα, σKβ production cross-sections and Kβ/Kα intensity ratios of Cr and Zn have been measured in pure metals and in different alloy compositions which have different composition values. And also, empirical and semi-empirical K-shell fluorescence yields (ωK) and Kβ/Kα intensity ratios from the available experimental data for elements with 23≤Z≤30 were calculated. The experimental data are fitted using the quantity (ωK/(1−ωK))1/4 vs. Z to deduce the empirical K-shell fluorescence yields and Kβ/Kα intensity ratios. The effects of alloying on the fluorescence parameters and bath temperatures on alloy compositions were investigated. Our analysis indicates that these effects arise from reorganization of atom and charge transfer mechanism in alloys.

K-shell fluorescence yields of barium and lanthanum

K-shell fluorescence yields for barium and lanthanum have been measured adopting simple 2π geometrical configuration and employing a weak 57Co radioactive source. A scintillation spectrometer with an NaI(Tl) detector of dimensions 44.5 mm diameter×50 mm thickness was employed for the detection and measurement of radiation. The results obtained are in good agreement with the best-fitted values of Hubbell et al. (1994) and also with the other experimental values, indicating that our simple method can be extended to determine fluorescence parameters of high Z materials.