A device for X‐Ray elemental mapping using annular radioisotope source

An energy‐dispersive system is described for elemental mapping by X‐ray fluorescence spectrometry. The present study describes the design of an X‐ray fluorescence spectrometer and presents its performance in elemental mapping applications. The spectrometer is based on a new ring‐shaped collimator with a pinhole in the center of it and a ring‐shaped Am‐241 isotope mounted in the collimator as a source for excitation of X‐ray fluorescence. The photons were detected by high‐resolution Si (Li) detector coupled to a multi‐channel analyser and cooled by liquid nitrogen. In this study, we used two samples; one of them was made from pure elemental powders, and the second one was a piece of a stone and three types of maps were plotted. In the maps type one, the areas of the elements were shown with a single color. These maps only show the location of the elements in the sample. In the maps type two, the area of each element was shown with different colors because of the count (intensity) related to the area. In the third type of the maps for each element, depending on the elements' position on the sample, the counts were plotted in three dimensions. The areas with higher intensity have greater height, and areas with lower intensity have lower altitude. These two last types of maps provide information about the homogeneity or heterogeneity of the elemental distribution in the samples. The spectrometer can perform non‐destructive analyses of samples and objects in the air. Copyright © 2017 John Wiley & Sons, Ltd.     

Approaches to solid sample preparation based on analytical depth for reliable X‐ray fluorescence analysis

In this paper, we discuss approaches to prepare solid samples for X‐ray fluorescence spectrometry (XRF). Although XRF can be used to analyze major and minor elements in various solid samples including powders and grains without dissolution techniques, to obtain reliable XRF results, the prepared sample must meet certain criteria related to homogeneity, particle size, flatness, and thickness. The conditions are defined by the analytical depth of fluorescent X‐rays from analytes, and the analytical depth can be estimated from the X‐ray absorption related to the energy of each X‐ray and the composition and density of the sample. For example, when the sample flatness and particle size are less than the analytical depth and the sample possesses homogeneity within a depth less than the analytical depth, the XRF results are representative of the entire sample. Furthermore, an appropriate sample thickness that is larger than the analytical depth or constant can prevent changes in fluorescent X‐ray intensity with variations in sample thickness. To obtain accurate and reproducible measurements, inhomogeneous solid samples must be pulverized, homogenized, and prepared as loose powder, powder pellets, or glass beads. This paper explains the approaches used to prepare solid samples for XRF analysis based on the analytical depths of fluorescent X‐rays. Copyright © 2016 John Wiley & Sons, Ltd.     

Integrating 3D images using laboratory‐based micro X‐ray computed tomography and confocal X‐ray fluorescence techniques

The application of non‐destructive imaging to characterizing samples has become more important as the costs of samples increase. Imaging a sample via X‐ray techniques is preferable when altering or even touching the sample affects its properties, or when the sample is fielded after characterization. Two laboratory‐based X‐ray techniques used at Los Alamos include micro X‐ray computed tomography (MXCT) and confocal micro X‐ray fluorescence (confocal MXRF). Both methods create a 3D rendering of the sample non‐destructively. MXCT produces a high‐resolution (sub‐µm voxel) rendering of the sample based upon X‐ray absorption; the resulting model is a function of density and does not contain any elemental information. Confocal MXRF produces an elementally specific 3D rendering of the sample, but at a lower (30 × 30 × 65 µm) resolution. By combining data from these two techniques, scientists provided a more comprehensive method of analysis. We will describe a MATLAB routine written to render each of these data sets individually and/or within the same coordinate system. This approach is shown in the analysis of two samples: an integrated circuit surface mounted resistor and a machined piece of polystyrene foam. The samples chosen provide an opportunity to compare and contrast the two X‐ray techniques, identify their weaknesses and show how they are used in a complementary fashion. Copyright © 2010 John Wiley & Sons, Ltd.     

X‐ray fluorescence analysis with a pyroelectric x‐ray generator

Several types of handy x‐ray fluorescence spectrometers are presented. The results obtained with a Niton spectrometer are presented as a goal to develop a laboratory‐made spectrometer using an Amptek Cool‐X pyroelectric x‐ray generator. A small and cheap charge‐up x‐ray emitting device and its spectrum are also presented. Handy x‐ray spectrometers are now progressing rapidly and the detection limits are in the range of a few ppm for certain elements. Copyright © 2005 John Wiley & Sons, Ltd.     

Trace element determinations in uranium by total reflection X‐ray fluorescence spectrometry using polychromatic X‐ray excitation

Suitability of polychromatic X‐rays has been assessed for the total reflection X‐ray fluorescence (TXRF) trace elemental determinations in aqueous solutions as well as uranium oxide certified reference materials. The method involves total reflection of X‐rays below a certain energy level on the TXRF sample support and exciting the analytes present in ng amount on these supports, measuring the TXRF spectra, processing the spectra, and finally determining the elemental concentrations. For uranium‐based samples, the samples were dissolved, main matrix uranium was separated from these solutions using solvent extraction, and trace elements were determined using aqueous phase following above approach. The method is simple and easier to implement compared with the monochromatic excitation but has similar or in some cases better detection limits compared with those obtained using monochromatic excitation. The details of the methodology, quality of analytical results, and detection limits are described and compared with those obtained using monochromatic excitation. Copyright © 2017 John Wiley & Sons, Ltd.     

A three‐crystal spectrometer for high‐energy resolution fluorescence‐detected X‐ray absorption spectroscopy and X‐ray emission spectroscopy at SSRF

A Johann‐type spectrometer for the study of high‐energy resolution fluorescence‐detected X‐ray absorption spectroscopy, X‐ray emission spectroscopy and resonant inelastic X‐ray scattering has been developed at BL14W1 X‐ray absorption fine structure spectroscopy beamline of Shanghai Synchrotron Radiation Facility. The spectrometer consists of three crystal analyzers mounted on a vertical motion stage. The instrument is scanned vertically and covers the Bragg angle range of 71.5–88°. The energy resolution of the spectrometer ranges from sub‐eV to a few eV. The spectrometer has a solid angle of about 1.87 × 0^?3 of 4π sr, and the overall photons acquired by the detector could be 10⁵ counts per second for the standard sample. The performances of the spectrometer are illustrated by the three experiments that are difficult to perform with the conventional absorption or emission spectroscopy. Copyright © 2016 John Wiley & Sons, Ltd.     

Quantitative elemental analysis of individual particles with the use of micro‐beam X‐ray fluorescence method and Monte Carlo simulation

The aim of the work was to develop a Monte Carlo (MC) method and combine it with micro‐beam X‐ray fluorescence (XRF) technique for determination of chemical composition of individual particles. A collection of glass micro‐spheres, made of NIST (National Institute of Standards and Technoly) K3089 material of known chemical composition, with diameters in the range of 25–45 µm was investigated. The micro‐spheres were measured in a scanning micro‐beam XRF spectrometer utilising X‐ray tube as a source of primary radiation. Results obtained for low Z elements showed high dependence on particle size. It was found that the root mean square of concentration uncertainty, for the all elements present in the particle, increases with growing sample size. More accurate results were obtained for high Z elements such as Fe–Pb, as compared to others. The elemental percentage uncertainty did not exceed 14% for any particular sample and 6% for the whole group of the measured micro‐spheres as an average. Results obtained by the Monte Carlo method were compared with other analytical approaches. Copyright © 2009 John Wiley & Sons, Ltd.     

A high‐resolution X‐ray fluorescence spectrometer and its application at SSRF

A high‐resolution X‐ray fluorescence spectrometer based on Rowland circle geometry was developed and installed at BL14W1 XAFS beamline of Shanghai Synchrotron Radiation Facility. The spectrometer mainly consists of three parts: a sample holder, a spherically curved Si crystal, and an avalanche photodiode detector. The simplicity of the spectrometer makes it easily assembled on the general purpose X‐ray absorption beamline. X‐ray emission spectroscopy and high‐resolution X‐ray absorption near edge spectroscopy can be carried out by using this spectrometer. X‐ray emission preliminary results with high‐resolution about 3 eV of Mn compounds were obtained, which confirmed the feasibility of the spectrometer. The application about Eu (III) retention on manganese dioxide was also studied using this spectrometer. Compared with conventional X‐ray absorption fine structure spectroscopy technique, the fluorescence peak of probed element [Eu (III) Lα] and matrix constituents (Mn Kα) were discriminated using this technique, indicating its superiority in fluorescence detection. Copyright © 2013 John Wiley & Sons, Ltd.     

Multivariate analysis of hyperspectral hard X‐ray images

This article describes methods to analyse and process hyperspectral hard X‐ray imaging data. We focus on the use of multivariate techniques that exploit the spectral information to make informed decisions on the material content within each pixel of an X‐ray image. These analysis methods have the ability to auto‐segment data without prior knowledge of the sample composition or structure, and are particularly useful for studying completely unknown, diluted or complex specimens. We demonstrate the methods on a variety of hard X‐ray images including X‐ray fluorescence and absorption data recorded using a hard X‐ray imaging spectrometer. The multivariate methods described are very powerful with the ability to segment, distinguish and, in some cases, identify different materials within a single X‐ray image. Potential uses of hyperspectral X‐ray imaging are discussed varying from materials science to industrial or security applications. Copyright © 2013 John Wiley & Sons, Ltd.     

X‐ray spectromicroscopy in soil and environmental sciences

X‐ray microscopy is capable of imaging particles in the nanometer size range directly with sub‐micrometer spatial resolution and can be combined with high spectral resolution for spectromicroscopy studies. Two types of microscopes are common in X‐ray microscopy: the transmission X‐ray microscope and the scanning transmission X‐ray microscope; their set‐ups are explained in this paper. While the former takes high‐resolution images from an object with exposure times of seconds or faster, the latter is very well suited as an analytical instrument for spectromicroscopy. The morphology of clusters or particles from soil and sediment samples has been visualized using a transmission X‐ray microscope. Images are shown from a cryo‐tomography experiment based on X‐ray microscopy images to obtain information about the three‐dimensional structure of clusters of humic substances. The analysis of a stack of images taken with a scanning transmission X‐ray microscope to combine morphology and chemistry within a soil sample is shown. X‐ray fluorescence is a method ideally applicable to the study of elemental distributions and binding states of elements even on a trace level using X‐ray energies above 1 keV.     

X‐ray tube spectral measurement method for quantitative analysis of X‐ray fluorescence analysis

Lα and Lβ X‐ray fluorescence spectra of a lead metallic sheet were measured using an energy dispersive X‐ray spectrometer by changing the X‐ray tube voltage and the material of the primary filter. The Lα to Lβ intensity ratio changed from Lα: Lβ = 3: 1 at 15 kV to Lα: Lβ = 1: 1 at 50 kV depending on the X‐ray tube voltage and the filter. The scattered X‐ray spectra of an acrylic slab instead of the sample in the sample holder were measured by changing the applied voltage and the material of the primary filter. The calculated values of the Pb Lα/Lβ intensity ratio of the metallic sheet using the Shiraiwa–Fujino formula by inserting the scattered X‐ray spectra of an acrylic plate as incident X‐ray spectra and the fundamental parameters taken from the Elam database were in good agreement with the experimental ones. We conclude that we can obtain an incident X‐ray spectrum approximately by measuring the scattered X‐ray spectrum without measuring the direct incident beam. Copyright © 2010 John Wiley & Sons, Ltd.     

Elemental mapping of frozen‐hydrated cells with cryo‐scanning X‐ray fluorescence microscopy

Visualizing the elemental distributions of cells and tissues is of growing importance in biology and medical science because such data deepen our understanding of the behavior of metal‐binding proteins and ions. Elemental mapping by X‐ray fluorescence analysis with a hard X‐ray nanobeam is very well suited for this purpose owing to its high sensitivity and high resolution. Using this technique, samples must be prepared without artifacts that are caused by treatments such as chemical fixation and staining procedures. In many studies of elemental mapping, sample preparation is not explicitly considered. To overcome this deficiency, we developed a cryo‐scanning X‐ray fluorescence microscope and installed it in the second experimental hutch of BL29XUL of SPring‐8. We used it to observe frozen‐hydrated cells that had been fixed by a quick‐freezing technique to preserve elemental data of the living state at an X‐ray energy of 11.5 keV. The distributions of K, Ca, Fe, Cu and Zn were successfully visualized. The distributions of these elements (especially those of K, Ca and Fe) differed from those in cells fixed with paraformaldehyde. Copyright © 2010 John Wiley & Sons, Ltd.     

Trace elemental determination by portable total reflection X‐ray fluorescence spectrometer with low wattage X‐ray tube

A specimen containing nanograms of Sb, rare earth elements, Pb, and Bi and a specimen containing a few nanograms each of As and Pb were measured using a portable total reflection X‐ray fluorescence spectrometer. Nanograms of Sb, rare earth elements, Pb, and Bi were detected. Although the As Kα line (10.54 keV) overlapped with the Pb Lα line (10.55 keV) in a spectrum of the specimen containing nanograms of As and Pb, the Pb Lβ line was detected. Therefore, the net intensity of the As Kα line was calculated using the Pb Lα/Lβ intensity ratio in a spectrum of a Pb standard solution and the net intensity of the Pb Lβ line in the spectrum of the specimen containing As and Pb. This result indicates that these two elements can be quantified by using the portable spectrometer. Commercially available bottled drinking water was also measured. The portable spectrometer detected several tens of ppb of V in the drinking water sample. Copyright © 2013 John Wiley & Sons, Ltd.     

A comparative study on the total reflection X‐ray fluorescence determination of low Z elements using X‐ray tube and synchrotron radiation as excitation sources

Detailed total reflection X‐ray fluorescence (TXRF) studies for the detection and quantification of low atomic number elements were carried out by using a laboratory dual source TXRF spectrometer equipped with a vacuum chamber and at the International Atomic Energy Agency multi‐purpose end‐station facility, operated at the XRF beamline of Elettra Sincrotrone Trieste, Italy. Multi‐elemental standard aqueous solutions of low Z elements (F, Na, Al, S, K, Sc, and Ti) with different elemental concentrations of 2, 10, 20, and 30 µg/ml were prepared and measured in both setups. The measurements at the synchrotron setup were performed in a scanning mode across the sample residue and perpendicular to the incident beam in order to account properly for a possible non‐uniform deposition of certain elements. The accuracy and the detection limits obtained from the TXRF measurements in both setups were determined and comparatively evaluated and assessed. Significant improvement in the TXRF detection limits at the synchrotron beamline end‐station was obtained for the elements with Z ≤ 13 (Al). Copyright © 2017 John Wiley & Sons, Ltd.     

Combined X‐ray microanalytical study of the Nd uptake capability of argillaceous rocks

Argillaceous rocks are considered as suitable host rock formation to isolate the high‐level radioactive waste from the biosphere for thousands of years. Boda Claystone Formation, the possible host rock formation for the Hungarian high‐level radioactive waste repository, has geologically and mineralogically been studied in detail, but its physico‐chemical parameters describing the retention capability of the rock needed further examinations. Studies were performed on thin sections subjected to 72 h sorption experiments using inactive Nd(III). Nd(III) has been used as a chemical analogue for transuranium elements of the radioactive waste to examine the ion uptake capability of the micrometre size mineral phases occurring in the rock. The elemental mapping of synchrotron radiation‐based microscopic X‐ray fluorescence (micro‐XRF) combined with scanning electron microscopy energy dispersive X‐ray analysis (SEM/EDX) has sufficient sensitivity to study the uptake capability of the different mineral phases on the microscale without the necessity of applying radioactive substances. Elemental maps were recorded on several thousand pixels using micrometre magnitude spatial resolution. By interleaving micro‐XRF and SEM/EDX data sets from the same sample area and applying multivariate methods, calcite and clay minerals could be identified as the main mineral phases responsible for Nd(III) uptake without using additional microscopic X‐ray diffraction mapping. It should be highlighted that the ion uptake capability of dolomite containing calcium and magnesium could be distinguished from the characteristics of calcite only by the interleaving of micro‐XRF and SEM/EDX data sets. The presence of minerals was verified by applying microscopic X‐ray diffraction point measurements. Copyright © 2015 John Wiley & Sons, Ltd.     

Optimized energy dispersive X‐ray fluorescence analysis of atmospheric aerosols collected at pristine and perturbed Amazon Basin sites

Elemental composition of aerosols is important to source apportionment studies and to understand atmospheric processes that influence aerosol composition. Energy dispersive X‐ray fluorescence spectroscopy was applied for measuring the elemental composition of Amazonian atmospheric aerosols. The instrument used was a spectrometer Epsilon 5, PANalytical B.V., with tridimensional geometry that reduces the background signal with a polarized X‐ray detection. The measurement conditions were optimized for low‐Z elements, e.g. Mg, Al, Si, that are present at very low concentrations in the Amazon. From Na to K, our detection limits are about 50% to 75% lower than previously published results for similar instrument. Calibration was performed using Micromatter standards, except for P whose standard was produced by nebulization of an aqueous solution of KH₂PO₄ at our laboratory. The multi‐element reference material National Institute of Standards and Technology–2783 (air particulate filter) was used for evaluating the accuracy of the calibration procedure of the 22 elements in our standard analysis routine, and the uncertainty associated with calibration procedures was evaluated. The overall performance of the instrument and validation of our measurements were assessed by comparison with results obtained from parallel analysis using particle‐induced X‐ray emission and another Epsilon 5 spectrometer. The elemental composition in 660 samples collected at a pristine site in the Amazon Basin and of 1416 samples collected at a site perturbed by land use change was determined. Our measurements show trace elements associated with biogenic aerosols, soil dust, biomass burning, and sea‐salt, even for the very low concentrations as observed in Amazonia. Copyright © 2014 John Wiley & Sons, Ltd.     

Confocal macro X‐ray fluorescence spectrometer on commercial 3D printer

Novel confocal X‐ray fluorescence (XRF) spectrometer was designed and constructed for 3D analysis of elementary composition in the surface layer of spatially extended objects having unlimited chemical composition and geometrical shape. The main elements of the XRF device were mounted on a moving frame of a commercial 3D printer. The XRF unit consists of a silicon drift detector and a low‐power transmission‐type X‐ray tube. Both the excitation and secondary X‐ray beams were formed and regulated by simple collimator systems in order to create a macro confocal measuring setup. The spatial accuracy of the mechanical stages of the 3D printer achieved was less than 5 μm at 100‐μm step‐size. The diameter of the focal spot of the confocal measuring arrangement was between 1.5 and 2.0 mm. The alignment of the excitation and secondary X‐ray beams and the selection of the measuring spot on the sample surface were ensured by two laser beams and a digital microscope for visualization of the irradiated spot. The elements of the optical system together with the XRF spectrometer were mounted on the horizontal arm of the 3D printer, which mechanical design is capable of synchronized moving the full spectroscopic device within vertical directions. Analytical capability and the 3D spatial resolution of the confocal spectrometer were determined. Copyright © 2017 John Wiley & Sons, Ltd.     

Experimental study of the efficiency of a SDD X‐ray detector by means of PIXE spectra

The efficiency of a silicon drift detector with ultrathin window was studied for energies between 0.27 and 25 keV. Experimental values of the X‐ray yields from samples of known stoichiometry were obtained by impact of 2 MeV protons. By using theoretical calculations of these yields the relative efficiency of the detector was evaluated. The results are compared with efficiency values obtained from the window transmission and the detector quantum efficiency. A quantitative analysis of a particle induced X‐ray emission spectrum for a reference sample was performed in order to evaluate the consistency of the data presented in this work. Copyright © 2013 John Wiley & Sons, Ltd.     

A multiplexed high‐resolution imaging spectrometer for resonant inelastic soft X‐ray scattering spectroscopy

The optical design of a two‐dimensional imaging soft X‐ray spectrometer is described. A monochromator will produce a dispersed spectrum in a narrow vertical illuminated stripe (～2 µm wide by ～2 mm tall) on a sample. The spectrometer will use inelastically scattered X‐rays to image the extended field on the sample in the incident photon energy direction (vertical), resolving the incident photon energy. At the same time it will image and disperse the scattered photons in the orthogonal (horizontal) direction, resolving the scattered photon energy. The principal challenge is to design a system that images from the flat‐field illumination of the sample to the flat field of the detector and to achieve sufficiently high spectral resolution. This spectrometer provides a completely parallel resonant inelastic X‐ray scattering measurement at high spectral resolution (～30000) over the energy bandwidth (～5 eV) of a soft X‐ray absorption resonance.     

A large‐solid‐angle X‐ray Raman scattering spectrometer at ID20 of the European Synchrotron Radiation Facility

An end‐station for X‐ray Raman scattering spectroscopy at beamline ID20 of the European Synchrotron Radiation Facility is described. This end‐station is dedicated to the study of shallow core electronic excitations using non‐resonant inelastic X‐ray scattering. The spectrometer has 72 spherically bent analyzer crystals arranged in six modular groups of 12 analyzer crystals each for a combined maximum flexibility and large solid angle of detection. Each of the six analyzer modules houses one pixelated area detector allowing for X‐ray Raman scattering based imaging and efficient separation of the desired signal from the sample and spurious scattering from the often used complicated sample environments. This new end‐station provides an unprecedented instrument for X‐ray Raman scattering, which is a spectroscopic tool of great interest for the study of low‐energy X‐ray absorption spectra in materials under in situ conditions, such as in operando batteries and fuel cells, in situ catalytic reactions, and extreme pressure and temperature conditions.