Characteristic X-ray Fluorescence Research Articles

Development and experimental evaluation of hybrid K-edge/X-ray fluorescence densitometer for uranium solution measurement

The hybrid K-edge/X-ray fluorescence densitometer (HKED) is a combination of K-edge absorption technology (KED) and characteristic X-ray fluorescence (XRF), which has the advantages of direct, fast and non-destructive determination, and is an ideal non-destructive measurement technology for uranium and plutonium concentrations. In this paper, a new HKED was developed, primarily utilizing an X-ray tube from COMET, alongside high-purity germanium (HPGe) and cadmium telluride (CdTe) detectors from AMETEK ORTEC. This manuscript delves into several variables that influence measurement outcomes under predefined experimental conditions and operational prerequisites to pinpoint critical parameters. It was discerned that the adoption of a 160 kV high voltage setting markedly diminishes experimental interferences, while the beam current, optimally set at 2 mA, not only ensures a linear correlation with the count rate but also maximizes the effective count detected. The incorporation of a 2 cm fixed-length iron rod along the trajectory between the sample and the detector, complemented by an additional 3 mm external absorber before the KED detector, effectively mitigates direct X-ray exposure, thereby enhancing transmittance values to attainable extents. Subsequent to the determination of these pivotal parameters, validation of the HKED system's efficacy was conducted via performance evaluation tests on a laboratory-scale HKED setup. Measurements undertaken for both KED and XRF across an interval ranging from 300 to 3000 s fell within the 2σ boundary, affirming the system's stability. Repeated measurements of 50 g/L and 150 g/L uranium solutions yielded KED precision rates of 0.56% and 0.19%, respectively. Moreover, linear regression analyses linking transmittance, characteristic X-ray fluorescence, and uranium concentrations across a spectrum of 0–150 g/L underscored the laboratory HKED instrument's robust analytical capabilities. Notably, the relative discrepancy between theoretical predictions and empirical findings for the 150 g/L uranium sample was minimized to a commendable 0.58%.

When one equals two: Chemometrics turns Mössbauer spectrometer into X-ray fluorescence one

Here we explore the feasibility of using classical Mössbauer spectroscopy setup in scattering geometry to assess the elemental composition of samples using characteristic X-ray fluorescence. Even though, the scintillation detector of Mössbauer spectrometer yields rather low spectral resolution spectra, this can be effectively compensated using chemometric data processing. This hypothesis was first checked with simulated spectra of steel samples and afterwards was confirmed with real experiments. The results of Ti, Cr, Mn, Ni, Nb and Mo quantification in real steel samples obtained from Mössbauer spectrometer were compared with those obtained with commercial energy dispersive X-ray fluorescence (EDXRF) spectrometer. In case of Ti, Cr and Ni the accuracy attained with Mössbauer spectrometer was similar to that of an ordinary commercial EDXRF device.

The study of X-ray full-field imaging method for low atomic number elements based on Compton scattering

Full-field X-ray fluorescence imaging cannot image low atomic number (Z < 12) materials because the characteristic X-ray fluorescence produced by low atomic number (Z < 12) materials is severely attenuated in air. In this paper, we propose a method to combine Compton scattering with full-field X-ray fluorescence imaging, which can realize the imaging of both metals (high atomic number) and organic materials (low atomic number), and compensate the defect that the conventional FF-XRFI technique cannot image materials with low atomic number such as organic materials. The imaging experiments were performed using two materials, zirconium metal and polyethylene, and the imaging results were optimized using a density filtering algorithm, and the results indicate that it is possible to use this method to image samples of high and low atomic number with resolution.

Single-Slice XRF Mapping of Light Elements in Frozen-Hydrated Allium schoenoprasum via a Self-Absorption-Corrected Hyperspectral Tomographic Reconstruction Approach.

3D and 2D-cross-sectional X-ray fluorescence analysis of biological material is a powerful tool to image the distribution of elements and to understand and quantify metal homeostasis and the distribution of anthropogenic metals and nanoparticles with minimal preparation artifacts. Using tomograms recorded on cryogenically prepared leaves of Allium schoenoprasum, the cross-sectional distribution of physiologically relevant elements like calcium, potassium, manganese, and zinc could be tomographically reconstructed by peak fitting followed by a conventional maximum-likelihood algorithm with self-absorption correction to reveal the quantitative cross-sectional element distribution. If light elements such as S and P are located deep in the sample compared to the escape depth of their characteristic X-ray fluorescence lines, the quantitative reconstruction becomes inaccurate. As a consequence, noise is amplified to a magnitude where it might be misinterpreted as actual concentration. We show that a tomographic MCA hyperspectral reconstruction in combination with a self-absorption correction allows for fitting of the XRF spectra directly in real space, which significantly improves the qualitative and quantitative analysis of the light elements compared to the conventional method as noise and artifacts in the tomographic reconstruction are reduced. This reconstruction approach can substantially improve the quantitative analysis of trace elements as it allows the fitting of summed voxel spectra in anatomical regions of interest. The presented method can be applied to XRF 2D single-slice tomography data and 3D tomograms and is particularly relevant for, but not limited to, biological material in order to help retrieve self-absorption corrected quantitative reconstructions of the spatial distribution of light elements and ultra-trace-elements.

Elemental composition x-ray fluorescence analysis with a TES-based high-resolution x-ray spectrometer

The accurate analysis of the elemental composition plays a crucial role in the research of functional materials. The emitting characteristic x-ray fluorescence (XRF) photons can be used for precisely discriminating the specified element. The detection accuracy of conventional XRF methodology using semiconductor detector is limited by the energy resolution, thus posing a challenge in accurately scaling the actual energy of each XRF photon. We adopt a novel high-resolution x-ray spectrometer based on the superconducting transition-edge sensor (TES) for the XRF spectroscopy measurement of different elements. Properties including high energy resolution, high detection efficiency and precise linearity of the new spectrometer will bring significant benefits in analyzing elemental composition via XRF. In this paper, we study the L-edge emission line profiles of three adjacent rare earth elements with the evenly mixed sample of their oxide components: terbium, dysprosium and holmium. Two orders of magnitude better energy resolution are obtained compared to a commercial silicon drift detector. With this TES-based spectrometer, the spectral lines overlapped or interfered by background can be clearly distinguished, thus making the chemical component analysis more accurate and quantitative. A database of coefficient values for the line strength of the spectrum can then be constructed thereafter. Equipped with the novel XRF spectrometer and an established coefficient database, a direct analysis of the composition proportion of a certain element in an unknown sample can be achieved with high accuracy.

IMBALANCE OF ESSENTIAL AND TOXIC ELEMENTS IN THE BIOSAMPLES OF PATIENTS WITH SURFACE GASTRITIS WITH DIFFERENT SECRETORY ACTIVITY

The results of the application of various nuclear physics methods (characteristic X-ray radiation, gammaactivation analysis, and X-ray fluorescence analysis) to the study of the imbalance of certain elements in various biological samples (blood, hair, gastric mucus) in patients with superficial gastritis with increased and decreased secretory activity. The detection limit ranged from 10-4…10-7 mas.% of the mass. Particular attention was paid to sample preparation and the study of the analytical capabilities of the methods. It is shown that in this pathology there is an increased content of essential elements in the hair and a significant content of conditionally toxic and toxic elements in the blood and gastric mucus.

Analysis of measurement accuracy of Zn–Fe alloy coatings under two take-off angles

The multilayer structure of the zinc-iron alloy coating leads to the online measurement accuracy of coating weight (mass) being slightly inferior to that of the zinc coating. Through offline and online comparative analysis of 20 samples with a weight of zinc-iron alloy coating between 30 and 50 g/m2, the average error of the sum of two-sided averages up to 8 g/m2. By studying the characteristic X-ray fluorescence intensity at two take-off angles, we established a calibration curve of 30–50 g/m2, and proposed a fast measurement method based on coordinate projection. Under the disturbance of zinc-iron alloy phase structure, the measurement error was ±1 g/m2 18 samples test manifest the average error of coating weight measurement reduced from 8 g/m2 to 0.56 g/m2. The accuracy increased from 91.28% to 98.64%.

Determination of low Z elements concentrations in geological samples by energy dispersive X-ray fluorescence with a back propagation neural network

Due to complex scattering from the sample dark matrix, absorption in the detector window and the competing Auger effect with higher cross-section for low Z elements (Z < 14), direct quantification of low Z elements by measuring characteristic X-ray fluorescence intensities during energy dispersive X-ray fluorescence (EDXRF) analysis of geological samples is challenging. This paper reports the chemometric quantitative analysis model of low Z elements (O, Na, Mg, and Al) in geological samples obtained by training the backpropagation neural network (BPNN) using the Compton scatter data combined with the concentrations of measurable elements. The training data is derived from the measured spectra of soil and rock standard samples and their synthetic samples configured with compounds. The standardized Compton scatter data and correlated element concentrations were used as the input data of the BPNN model. The prediction results of the BPNN model show that the coefficient of determination (R2) values between true and predicted concentrations for O, Na, Mg, and Al are both >0.95. It implied that the modeling approaches significantly overcome matrix effects between the concentrations of low Z elements and Compton scatter peaks. So, the method has the potential for being widely used in the analysis of samples rich in low Z elements.

Shrinkable Hydrogel-Enhanced Biomarker Detection with X-ray Fluorescent Nanoparticles.

This paper reports a new method to enhance the sensitivity of nanoparticle-based protein detection with X-ray fluorescence by exploiting the large volume reduction of hydrogel upon dehydration. A carboxylated agarose hydrogel with uniaxial microchannels is used to allow rapid diffusion of nanoparticles and biomolecules into the hydrogel and water molecules out of the hydrogel. Carboxylated hydrogels are modified to capture protein biomarkers and X-ray fluorescence nanoparticles (iron oxide nanoparticles) are modified with antibodies that are specific to protein biomarkers. The presence of protein biomarkers in solution binds the nanoparticles on the hydrogel channels. The dehydration of hydrogels leads to a size reduction of over 80 times, which increases the number of nanoparticles in the interaction volume of the primary X-ray beam and the intensity of characteristic X-ray fluorescence signal. A detection limit of 2 μg/mL for protein detection has been established by determining the number of nanoparticles using X-ray fluorescence.

In situ experimental measurement of mercury by combining PGNAA and characteristic X-ray fluorescence

In our previous research, a new detection method was proposed to measure Hg and Pb simultaneously by combining Prompt Gamma-ray Neutron Activation Analysis (PGNAA) and X-ray Fluorescence (XRF) and proved by the Monte Carlo N-Particle (MCNP) simulation code. For further experimental verification, a combined measurement experimental facility, comprising an 241Am–Be neutron source, SAINT-GOBAIN Bismuth Germanate (BGO) as the γ-ray detector, and an NaI detector with 25 μm Be window as the X-ray detector, was presented. Specifically, the characteristic X-ray fluorescence of the Hg directly induced in this experimental facility was utilized to improve the limits of detection (LOD) of Hg instead of traditional excitation sources. The simulation and experiment results indicated that LOD for Hg by the combined measurement instrument was 19.4 mg kg−1. The empirical formula of the calibration curve in this method was given based on the aforementioned calculations.

Explosive detection and identification using X-ray fluorescence and thermal fingerprint of silica encapsulated nanoparticles

This paper describes a nanoparticle-based explosive’s marking technique for pre-blast detection and post-blast identification of explosives. Trace explosive containing a panel of metallic nanoparticles (metals and alloys) can be detected by nanoparticles’ characteristic X-ray fluorescence, and identified by their unique thermal properties (i.e., composition dependent melting temperatures and discrete and sharp melting peaks in differential scanning calorimeter). The selected nanoparticles added into explosive are easy to manufacture and safe to use, do not affect explosive performance, can survive blast, thus will greatly reduce threats of unlawful uses of explosives.

Physical aspects of gold nanoparticles as cancer killer therapy

The objective of this research is to increase the diagnostics and the radiotherapy efficiency enhancing the effective atomic number of cancer tissues using the injection of gold nanoparticles. The proposed method employs spheroidal gold nanoparticles, with an average diameter of about 10 nm, prepared using Nd:YAG laser ablation in water. Their distribution in tumor tissues can be obtained by local injection, by transport through the blood flux or by using functionalized nanoparticles transported in specific organs. The characterization of the nanoparticles was made by electron microscopy, characteristic X-ray fluorescence and optical absorbance investigation in the UV–visible region. The calculations demonstrate that the mass attenuation coefficients for X-rays and the proton stopping power in the tissue with nanoparticles increase significantly using a 0.1% concentration in weight. In conclusion, the presence of gold nanoparticles in the cancer tissues enhances significantly the cross section of the photoelectric effect for X-ray absorption and the stopping power of incident energetic protons, allowing the higher dose release. The releasing of nanoparticles only in the tumor site and not in the healthy tissues remains the most important problem to be resolved. The advances of this research concern, mostly, on acquisition of knowledge about the employment of nanoparticles locally injected in tumor site, to significantly enhance the contrast image and the dose released during radiotherapy with X-rays and proton beams.

Feasibility study of a new method to measure fast neutron flux by neutron-induced X-ray fluorescence method

A new method is proposed to detect fast neutron flux: the neutron-induced X-ray fluorescence method. In this method, the neutrons are firstly converted to charged particles, and then the charged particles interact with the target to generate the characteristic X-ray fluorescence. Finally, the Kα X-ray emission from the target is detected for measurement of the neutron flux. On the basis of this method, the structure of the detection device is designed: it is composed mainly of a layer of a fast neutron converter and a layer of the target. The Geant4 Monte Carlo simulation toolkit is used to optimize the detection device. According to the simulation results, the detection device is manufactured so as to perform the feasibility verification experiments. In the experiments, a D-T neutron generator is used as the neutron source, and the number of neutrons is changed in two ways: by change of the working voltage of the neutron generator or by change of the measurement time. The experimental results show that there is a good linear relationship between the number of neutrons and the Kα X-ray counts when the measurement time is changed. When the working voltage of the neutron generator is changed, a 3He proportional counter is used as a reference detector. The results show that the trend of the Kα X-ray counts is in good agreement with the trend for the 3He proportional counter. It is proved that this method is feasible for fast neutron flux measurement.

Studying the Emission of X-Ray Quanta, Neutrons, and Charged Particles from Deuterated Structures Irradiated with X-Rays

The emission of X-ray quanta, neutrons, and charged particles from deuterated structures under X-ray irradiation is studied. Targets (deuterated chemical-vapor-deposited (CVD)-diamond, palladium, zirconium, and titanium) are irradiated with the use of an X-ray tube equipped with a polycapillary lens with an energy of up to 30 keV and an X-ray tube equipped with a collimator with an energy of up to 25 keV. Different types of detectors, such as a multichannel neutron detector based on He-3 counters, a CR-39 plastic track detector, and silicon surface barrier detectors, are used. The emission of neutrons with an energy of above 10 MeV and alpha particles with an energy range of 7–15 MeV is revealed. This result indicates the possibility of stimulating multiparticle fusion reactions between deuterium nuclei in solid deuterated structures. The analysis of X-ray fluorescence spectra demonstrate the existence of “additional” peaks, which cannot be identified by any characteristic X-ray fluorescence line. Their appearance cannot be associated with any known element or diffraction process. The nature of the origination of the “additional” peaks requires special study.

A novel technique for online slurry grade detection based on EDXRF

The accuracy of energy dispersion X-ray fluorescence spectrometry (EDXRF) decreases via the online detection of slurry grade, which is due to the matrix difference caused by varying slurry components and processes. Among these, the most significant influence is the water content in the slurry, which reduces the X-ray fluorescence intensity of target elements that the detector receives. In this paper, a novel online detection method based on a correction model of X-ray fluorescence intensity is proposed. Using the mineral particle settling model as a foundation, the minimum slurry velocity was first derived to satisfy the condition of pulp content uniformity. Then, the impact of slurry concentration on the X-ray fluorescence intensity was analyzed. An intensity correction model was built, which accounted for the impact of water in slurry on the characteristic X-ray fluorescence intensity of the target elements. The overall methodology was thoroughly validated through several experiments, and was compared with the traditional EDXRF method. The experimental results indicated that the standard deviation of the target’s elemental slurry grade dropped by more than 60% for lead and 40% for zinc. Meanwhile, the average relative error of the slurry’s elemental grade was reduced by more than 80% for lead and 90% for zinc. The accuracy and stability of online slurry grade detection were therefore significantly improved.

Use of portable XRF: Effect of thickness and antecedent moisture of soils on measured concentration of trace elements

The use of portable X-ray fluorescence (PXRF) for rapid measurements of concentrations of trace elements in soils is increasing. The purpose of this study was to assess in a systematic way the influence of soil moisture and sample thickness on concentrations of Ni, Zn, Cd, and Pb in a mixture of glass beads as well as Windsor loamy sand and Webster loam soils. The Windsor soil was collected from near Lebanon, NH, and the Webster soil was sampled from Story County, IA. In this context, the efficacy of the Compton Normalization (CN) calibration method to correct for changes in soil moisture was determined. Despite CN calibration, an inverse correlation between PXRF measured concentrations and soil moisture was observed. The magnitude of this effect depends upon the energy of the characteristic X-ray fluorescence of each element, with those emitting lower energy X-ray fluorescence being more greatly influenced. Moisture contents ranging from 0.09 to 0.26 cm3 cm−3 were found to generate trace element concentrations with no statistical difference, with significantly lower concentrations reported at greater moisture contents. In addition, measured concentrations of each trace element increased with increasing sample thickness until a constant measured concentration was attained, which was also correlated with the energy of the characteristic X-ray fluorescence of the corresponding trace element. Ni, with the lowest energy fluorescence, obtained constant measured concentration at 3 mm for all matrices, whereas a sample thickness of up to 10 mm was needed for Cd. In order to account for energy differences across a range of trace elements and matrices, the use of PXRF should be limited to soil samples having a thickness of at least 10 mm.

Study of the Impact of Sample Thickness on Thin Film Method X-Ray Fluorescence Spectrum Measurement

The mixed samples of nylon film enrichment of Cr, Pb and Cd three elements and glass fiber membrane filter were as the research object. With the method of superposition of membrane filter, the XRF spectra were measured under different thin film samples thicknesses. According the changes of characteristic XRF of Cr, Pb and Cd elements in the mixed sample and Ca, As and Sr elements in glass fiber membranes, the effects of sample thickness on thin film method XRF spectrum measurement were studied. The study results showed that the effects of thin film sample thickness on the fluorescent properties of elements with characteristic spectral lines in different energy ranges were different. The energy of characteristic spectral lines was greater, the loss of element characteristic X-ray fluorescence when it passed through membrane and reached detector was less. But matrix effect caused by thin film sample thickness increase was stronger with the energy of characteristic spectral lines greater. The background fluorescent intensity in corresponding characteristic spectral line location was greater. So the impact of matrix effect caused by sample thickness increase on thin film method XRF spectrum measurement sensitivity was greater. For elements with low energy characteristic spectral lines (energy≤7 keV), the way of increasing thin film sample thickness in order to increase the mass-thickness concentration of component measured, can not effectively improve the sensitivity of thin film method XRF spectrum measurement. And thin film samples thickness within 0.96 mm is conductive to the measurement and analysis of XRF spectrum. For element with higher energy characteristic spectra lines(energy＞7 keV), the sensitivity of XRF spectrum measurement can be appropriately increased by the way of increase thin film sample thickness in order to increase the mass-thickness concentration of component measured. And thin film samples thickness within 0.96～2.24 mm is more conductive to the measurement and analysis of XRF spectrum. The study provides an important theoretical basis for thin sample preparation and enrichment technology of thin film method X-ray fluorescence spectrum analysis the atmosphere and water heavy metal.

Ancient bronze coins from Mediterranean basin: LAMQS potentiality for lead isotopes comparative analysis with former mineral

Bronze coins coming from the area of the Mediterranean basin, dated back the II–X Cent. A.D., were analyzed using different physical analytical techniques. Characteristic X-ray fluorescence was used with electrons and photons, in order to investigate the elemental composition of both the surface layers and bulk. Moreover, the quadrupole mass spectrometry coupled to laser ablation (LAMQS technique) in high vacuum was used to analyse typical material compounds from surface contamination. Mass spectrometry, at high resolution and sensitivity, extended up to 300amu, allowed measuring the 208Pb/206Pb and 207Pb/206Pb isotopic ratios into the coins. Quantitative relative analyses of these isotopic ratios identify the coin composition such as a “fingerprint” depending on the mineral used to extract the lead. Isotopic ratios in coins can be compared to those of the possible minerals used to produce the bronze alloy. A comparison between the measured isotope ratios in the analyzed coins and the literature database, related to the mineral containing Pb as a function of its geological and geophysical extraction mine, is presented. The analysis, restricted to old coins and the mines of the Mediterranean basin, indicates a possible correlation between the coin compositions and the possible geological sites of the extracted mineral.

Analysis of geometric factors for an X-ray fluorescence analyzer designed via the Monte Carlo method

This paper presents a theoretical study on the design of an X-ray fluorescence (XRF) analyzer. The relative geometric positions of the analyzer’s source, detector and specimen are emphasized, which impacts the analyte’s characteristic X-ray fluorescence counts. The theoretical formula for the X-ray fluorescence intensity was derived. The geometric factors (angle and distance) were simulated using Monte Carlo Neutron-Particle Transport Code MCNP5. The Cu’s X-ray characteristic peak counts were calculated. These Monte Carlo model calculations analyzed two types of geometry changes. The best geometric positions for the XRF analyzer had the incident angle for the excitation source (β) equivalent to the exit angle for the specimen’s characteristic X-ray (β). The maximal characteristic X-ray peak counts were obtained when α and β were orthogonal, and the minimum counts were obtained when parallel. To increase the fluorescence counts, the source and detector should be set as close to the specimen as possible. This method and these conclusions can provide technical guidance for designing XRF analyzers.

XRF Standardless Comparison of Mining Head and Tail Grades to Screen and Display Ore Processing Recoveries

Separation of target elements or minerals from their host rock or ore is essential to successful mining operation. The inevitable loss of a portion of the desired material that accompanies each step in the extraction process must be documented to develop the operational protocol. Superposition of the characteristic X-ray fluorescence spectra of head (crushed rock ore particles, pre-processing) and tail (post-processing particles) samples provides a direct visual comparison of relative peak sizes, and thereby the relative concentrations, of elements of interest. If the head and tail peaks are identical, none of the element was recovered in the extraction process. At the other extreme if the tail peak “flat lines”, i.e., there is no peak, there was 100% recovery of that element. Standardless visual comparison is valid if the same mass of identical starting material is incorporated into the head and tail sample analysis pucks, and XRF analytical conditions are identical. The considerable time and expense of acquiring and calibrating the standards associated with XRF analysis of 75 or more elements are avoided, a significant advantage during initial broad screening of an experimental extraction procedure. Full quantitation by XRF or an alternate technique can proceed at a later project stage, if desired. The approach retains and presents all features of the original data, thus eliminating questions about data quality, standards and their calibration, and data manipulation in processing from raw counts to concentrations in printout tables. This form of display is ideal for both the mining professional and such less technical groups as corporate staff, investors, regulators, and the public. Examples presented herein are for heap leaching; the protocol can be applied as well to any of the other traditional ore processing and beneficiation procedures, e.g., gravity concentration, magnetic and electrical separation, froth flotation, and ore sorting.