X-ray Fluorescence Spectra Research Articles

Long‐term stability of invisible X‐ray fluorescence identification tags

AbstractThe traditional labelling of archive documents (e.g., hand stamping) entails several limitations. It could affect the aesthetic value of the archive document and is easy to find and remove in case of the theft of the document. The use of a label that would not be easily visible by the naked eye would resolve both of these problems. One possibility in designing such label is the use of the elements that have a good response in X‐ray fluorescence (XRF) spectrum, are not disturbing in colour, and are not usually present in the archive materials themselves. This study focuses on such type of labelling, specifically, the tags based on the oxides of lanthanum, dysprosium, samarium, gadolinium, and niobium. For the material to be taken into account by the community, it has to fulfil several important characteristics, such as harmlessness to the archival documents, non‐toxicity, or long‐term stability. In the study, the long‐term stability of these tags was studied on model samples of lignocellulose materials subjected to several types of artificial ageing. The colour changes and changes in the intensity of the responses of the individual elements in the XRF spectra were evaluated. To simulate the practical use, the tags of minimal visibility to the naked eye were printed on samples of real archive materials, and their potential for detection using a handheld XRF spectrometer was studied. Both of the research parts should help bring this type of labelling closer to the field application.

Fluorescent N/Al Co-Doped Carbon Dots from Cellulose Biomass for Sensitive Detection of Manganese (VII).

Development of metallic and nonmetallic heteroatom doped carbon dots have gained attention due to their enhanced physicochemical and photoluminescence properties. In this study, a facile one pot hydrothermal carbonisation approach was taken to synthesise nitrogen, aluminum co-doped carbon dots (N/Al-CDs) with a photoluminescence quantum yield of 28.7%. Durian shell, a cellulose biomass waste, was used as the primary carbon source and compared to previously reported cellulose based carbon dots, this study presents one of the highest quantum yields. The structural and fluorescent properties of the synthesised N/Al-CDs were characterized through X-ray photoelectron spectroscopy (XPS), fluorescence spectra, and Fourier transform infrared spectroscopy (FTIR). The maximum emission was at 415nm upon excitation at 345nm. The synthesised N/Al-CDs were resistant to photobleaching and highly photostable within the pH, ionic strength and temperature variations investigated. The transmission electron microscopy (TEM) images showed particles were quasi-spherical and well dispersed with an average diameter of 10.0nm. Further, the N/Al-CDs was developed as a fluorescence sensor for highly selective and sensitive detection of Mn (VII) ions. A linear relationship was developed over a concentration range of 0-100μM while the limit of detection was 46.8nM. Application of the sensor for detection of Manganese (VII) to two real water samples showed relative standard deviation was less than 3.9% and 1.3%, respectively.

Investigation of the interaction of ion beams and X-ray quanta with deuterated crystal structures at the HELIS facility

The results of studies of the interaction of ion beams and X-ray quanta with deuterated crystal structures at the HELIS facility (LPI) are presented. Results on research of DD-reactions in deuterated crystal structures at deuteron energies 10 - 25 keV show significant enhancement effect. It is shown that the effect of the beams of ions Ne+ and H+ at energies in the range of 10 - 25 keV and a beam of X-radiation of 20 - 30 keV for deuterated target leads to stimulation of DD-reaction. For the target of CVD-diamond it is showed that the orientation of the sample with respect to the deuteron beam affects the neutron yield. Targets (deuterated CVD diamond, palladium, zirconium and titanium) were irradiated with both ion beams and X-ray quanta using an X-ray tube with an energy of up to 30 keV. Analysis of X-ray fluorescence spectra from deuterated targets of CVD diamond and palladium revealed "additional" peaks that are not identified by any of the characteristic radiation lines. Their appearance cannot be connected with any known element, as well as with diffraction processes.

Peakaboo: Advanced software for the interpretation of X-ray fluorescence spectra from synchrotrons and other intense X-ray sources

Abstract Peakaboo is a platform for the analysis of full spectrum synchrotron X-ray fluorescence (XRF) map data. It offers robust, automated fitting of XRF spectral peaks, increasing the sensitivity to trace chemical elements. Large arrays of spectral data can also be processed into element maps to define spatial relationships. The modifications to Peakaboo introduced since 2017 are particularly designed to help new users to become rapidly competent in the handling of complex XRF spectra. Some of the most important innovations of the software are described below. Finally, we share examples of its application in Earth and Environmental Sciences.

Evaluation of X‐Ray Fluorescence Spectroscopy as a Tool for Nutrient Analysis of Pea Seeds

ABSTRACTThis research was conducted to evaluate the utility and reliability of X‐ray fluorescence (XRF) spectroscopy to analyze macro‐ (K and Ca) and micronutrients (Mn, Fe, Cu, Zn, and Se) in pea (Pisum sativum L.) seeds. The pea seed samples were ground into flour and pelleted to collect the XRF spectra. Seventy‐three pea seed samples were selected to cover the expected concentration ranges for each element to develop calibration curves by correlating the XRF results with atomic absorption spectroscopy (AAS). The XRF results were validated by a systematic comparison of data obtained from AAS on a set of 80 additional and independent pea seed samples. Element concentrations were also predicted using the fundamental parameter approach collectively for 153 samples. For all the calibration curves, the R2 value was >0.8, except for K (0.54). For Mn, Fe, Cu, Zn, and Se, the XRF predictions were similar to AAS measurements at a 95% confidence level. Similar results were obtained with the fundamental parameter approach except for Fe for which significant bias of ∼6 mg kg−1 was calculated. Except for K, R value for all the validation curves was >0.85. Thus, the results obtained using XRF and the fundamental parameter approach were statistically not different from the AAS method. This study demonstrated that the XRF technique is a fast and reliable, nondestructive, and noninvasive analytical tool for mineral analysis, particularly for transition metals, does not produce waste, and requires no chemical reagents.

Corrosion Protection of Monel Alloy Coated with Graphene Quantum Dots Starts with a Surge

There has been an active interest in protecting metals and alloys using graphene coating. The mechanism by which corrosion protection occurs has not been well understood as the couple involved are both good electron conductors. In this work, we demonstrate that Monel alloy coated with graphene quantum dots (GQD) changes the corrosion rate with a surge (increase) caused by the galvanic coupling of the two materials. This surge results in the protective layer formation on Monel to inhibit the corrosion. X-ray fluorescence spectrum of Monel (400) alloy showed the composition of it as Ni (67.05%) and Cu (29.42%). The Tafel experiments carried out in NaCl and Na2SO4 electrolytes showed an initial enhancement of the corrosion rate followed by a decrease upon successive polarizations. Monel coated with graphene oxide (an insulator) shows no initial enhancement of corrosion rate; the coated samples showed a lower corrosion rate in comparison to the uncoated samples. X-ray fluorescence, Fourier Transform spectroscopy (FTIR) and Raman imaging studies have been carried out for understanding this transformation. Distinct peaks due to Ni-O stretching and Ni-O-H bending vibration were observed in the FTIR spectrum.

Syntheses, Crystal Structures and NBO Calculation of Two New Zinc(II) Coordination Polymers

Two new Zn(II) coordination polymers based on bis(imidazol), namely, [Zn(hba)2(bib)]n(1) and [Zn(NAA)(bib)1.5]n·nNO3−·3nH2O (2) (Hhba = 3-hydroxybenzoic acid, HNAA = 1-naphthyl acetic acid, bib = 1,4-bis(imidazol-1-yl)-butane) have been successfully synthesized under hydrothermal conditions. Their structures have been determined by single crystal X-ray diffraction analyses, elemental analyses, IR, TG and fluorescence spectrums. Complex 1 shows a one-dimensional zigzag chain structure. Complex 2 exhibits two-dimensional network structure. The intermolecular hydrogen bonding and π–π stacking interactions extend the complexes 1 and 2 into supramolecular architectures and play an important role in stabilizing complexes 1 and 2. Furthermore, complex 1 exhibits intense blue luminescence and appears to be a good candidate for novel hybrid inorganic–organic photoactive materials, while no photoluminescent response was observed for complex 2. In addition, we analyzed the Natural Bond Orbitals (NBO) of 1 and 2 using the PBE0/LANL2DZ method in the Gaussian 09 Program. The calculations showed the obvious covalent interaction between the coordinated atoms and Zn(II) ion. Two new Zn(II) coordination polymers based on bis(imidazol), namely, [Zn(hba)2(bib)]n(1) and [Zn(NAA)(bib)1.5]n·nNO3−·3nH2O (2) have been successfully synthesized under hydrothermal conditions. Their structures have been determined by single crystal X-ray diffraction analyses, elemental analyses, IR, TG and fluorescence spectrum. Complex 1 shows a one-dimensional zigzag chain structure. Complex 2 exhibits two-dimensional network structure. The intermolecular hydrogen bonding and π–π stacking interactions extend the complex 1 and 2 into supramolecular architectures and play an important role in stabilizing complex 1 and 2. In addition, we analyzed Natural Bond Orbital (NBO) of 1 and 2 in using the PBE0/LANL2DZ method built in Gaussian 09 Program. The calculation results showed the obvious covalent interaction between the coordinated atoms and Zn(II) ion.

Nuclear Reactions under Irradiation of Deuterated Structures by X Rays

Measurements of emission from nuclear reaction products (neutrons and protons) have been carried out appearing in the deuterated structures of textured CVD diamond, palladium, titanium, and zirconium under irradiation with a beam of X rays using independent methods (neutron detector based on He-3 counters, Si surface-barrier semiconductor detectors and CR-39 track detector). The possibility of enhancement of both DD reaction and multi-particle deuterium fusion by the beam of X rays with energy ranging 20–30 keV in solid deuterated targets has been established. Analysis of X-ray fluorescence spectra of the target bombarded by beams of ions has revealed “additional” peaks, the occurrence of which cannot be related to any of the known elements, and requires separate study.

The Total-Reflection X-Ray Fluorescence Yield Formed by a Waveguide Resonator under Conditions of Ion Beam Excitation

The features of methods for total-reflection X-ray fluorescence analysis with proton-induced X‑ray fluorescence emission are described. A setup for obtaining X-ray fluorescence spectra under the conditions of proton-beam excitation has been developed using these methods. The setup is based on a specially designed planar X-ray waveguide resonator. The features of the new experimental diagnostic method in the unique research facility (UNU no. 45) of the Sokol-3 analytical ion-beam complex are discussed; some attention has been paid to the description of the capabilities of this facility.

Prompt Screening of the Alterations in Biochemical and Mineral Profile of Wheat Plants Treated with Chromium Using Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy and X-ray Fluorescence Excited by Synchrotron Radiation

With mounting pressure of heavy metal pollution on agriculture, the demand of practical tools and protocols for nondestructive, pre-visual detection of plant response towards heavy metals has received great impetus. Advances in modern spectroscopic techniques such as synchrotron radiation X-ray fluorescence and attenuated total reflectance Fourier transform infrared spectroscopy have the capability of providing a complete picture of the metabolic events taking place in plants stressed with heavy metals without subjecting the sample to pre-processing. The present study explores the utility of synchrotron radiation X-ray fluorescence and attenuated total reflectance Fourier transform infrared spectroscopy along with multivariate analysis for the detection of the response as spectral indices of wheat seedlings towards chromium treatment. For this, wheat has been grown under optimized growth conditions and exposed to chromium at concentrations from 20 to 100 µM. The synchrotron radiation X-ray fluorescence spectra of control and chromium exposed seedlings show that exposure to chromium leads to its accumulation in the leaves of wheat seedlings which results in a reduction of the uptake of calcium, potassium, manganese iron, copper and zinc by the seedlings. The alterations in the biochemicals of wheat seedlings as a result of chromium exposure have been assessed by attenuated total reflectance Fourier transform infrared spectroscopy. Analysis of the infrared data reveals that chromium significantly alters the spectral signatures of cellulose, pectin, hemicelluloses, lignin, amide II, amide I and lipid in the leaves of wheat seedlings. The observed changes are dependent on the dose of chromium. The spectral signatures obtained in this study serve as important monitoring indices for observing alterations in the physiological, biochemical and metabolic status of plants under heavy metal stress.

X-ray spectroscopy with an AlInP photodiode

Abstract A custom-made Al 0.52 In 0.48 P p + -i-n + circular mesa X-ray photodiode ( 200 μ m diameter; 2 μ m i layer thickness) has been investigated for its use in photon counting X-ray spectroscopy within the energy range 4.95 keV to 21.17 keV. This is the widest energy range so far used to characterize an AlInP X-ray detector. High-purity X-ray fluorescence calibration samples were excited by a Mo target X-ray tube to give characteristic energy photons with which to illuminate the detector. X-ray fluorescence spectra were accumulated with the Al 0.52 In 0.48 P X-ray detector coupled to a custom-made charge-sensitive preamplifier (both operated at a temperature of 30 °C ± 2 °C). The charge output linearly increased with X-ray photon energy. The energy resolution (Full Width at Half Maximum, FWHM) degraded from 0.99 keV ± 0.02 keV (80 e − rms) at 4.95 keV to 1.12 keV ± 0.02 keV (89 e − rms) at 21.17 keV. The increase of the FWHM with increased energy exceeded the increase expected as a consequence of Fano noise. Hence, the presence of energy dependent incomplete charge collection noise was suggested. The count rate linearly increased with increasing incident X-ray flux across the investigated flux range, up to ∼ 3 . 8 × 105 photons s−1 cm−2.

Formation and Evolution Mechanism for Carbonaceous Deposits on the Surface of a Coking Chamber

This work aimed to investigate the carbonaceous deposits on the surface of the coking chamber. Scanning electron microscopy (SEM), X-ray fluorescence spectrum (XRF), Fourier transform infrared spectrometer (FTIR), Raman spectroscopy, X-ray diffraction spectrum (XRD), and X-ray photoelectron spectroscopy (XPS) were applied to investigate the carbonaceous deposits. FTIR revealed the existence of carboxyl, hydroxyl, and carbonyl groups in the carbonaceous deposits. SEM showed that different carbonaceous deposit layers presented significant differences in morphology. XRF and XPS revealed that the carbonaceous deposits mainly contained C, O, and N elements, with smaller amounts of Al, Si, and Ca elements. It was found that in the formation of carbonaceous deposits, the C content gradually increased while the O and N elements gradually decreased. It was also found that the absorbed O2 and H2O took part in the oxidation process of the carbon skeleton to form the =O and –O– structure. The oxidation and elimination reaction resulted in change in the bonding state of the O element, and finally formed compact carbonaceous deposits on the surface of the coking chamber. Based on the analysis, the formation and evolution mechanisms of carbonaceous deposits were discussed.

Key inhibitory mechanism of external chloride ions on concrete sulfate attack

To explore the key inhibitory mechanism of external chloride ions on concrete sulfate attack, long-term partial- and full-immersion experiments of concrete in chloride solutions and chloride and sulfate composite solutions were performed. As corrosion time begins, visual inspection, compressive strength, and ultrasonic velocity were periodically observed or tested. Moreover, the micro-morphology, the contents of Cl and S elements in concrete, and the transport speeds of Cl− and SO42− ions through concrete were investigated by using scanning electron microscope, X-ray fluorescence spectrum, and chemical analysis. Chloride ions neither have corrosive effects on concrete nor effects on concrete physical and mechanical properties, which is the prerequisite for chloride ions in inhibiting concrete sulfate attack. In the case of combined solutions, the transport speed of Cl− ions into concrete is evidently higher than that of SO42− ions. Then, chloride ions enter concrete early and form Friedel's salt with AFm or with C3A and Ca(OH)2 in concrete, which inhibits the transport of SO42− ions into concrete and reduces the formation of expansive corrosion products of ettringite or gypsum. Thus, the sulfate attack on plain concrete is alleviated. Based on the inhibitory mechanism of Cl− ions on concrete sulfate attack, the presence of Cl− ions cannot completely avoid concrete sulfate attack but can partially reduce sulfate risk on concrete.

Characterization of Slag Cement Mortar Containing Nonthermally Treated Dried Red Mud

In this study, a method was suggested to produce dried powder from red mud (RM) sludge with 40%–60% water content without heating. The RM sludge is discharged from the Bayer process, which is used to produce alumina from bauxite ores. Nonthermally treated RM (NTRM) powder was produced by mixing RM sludge (50%), paper sludge ash (PSA, 35%), and high-calcium fly ash (HCFA, 15%). The physicochemical properties of NTRM were investigated by analyzing its water content, X-ray fluorescence spectra, X-ray diffraction patterns, and particle size. Moreover, to examine the applicability of NTRM as a construction material, slag cement mortar in which 20 wt% of the binder was replaced with NTRM was produced, and the compressive strength, porosity, and water absorption rate of the mortar were evaluated. Results indicated that NTRM of acceptable quality was produced when the water content in RM sludge decreased and CaO contained in PSA and HCFA reacted with moisture and formed portlandite. The NTRM-mixed mortar requires further examination in terms of durability because of the increased capillary voids and high water absorption rate, but its compressive strength is sufficient to enable its use in sidewalks, bike roads, and parking lots.

X-ray fluorescence and visible near infrared sensor fusion for predicting soil chromium content

Anthropogenic activities, such as sewage irrigation and application of pesticides and fertilizers, are the main cause of chromium (Cr) contamination in agricultural soils. Cr contamination reduces soil quality and threatens environmental and human health. Conventional Cr measurement methods, although accurate, involve complex sample processing steps and sophisticated laboratory analysis, which are time-consuming, costly, and often environmentally unfriendly. X-ray fluorescence (XRF) and visible near-infrared (vis–NIR) spectroscopy have been recognized as alternatives to measure soil heavy metal contamination in a cheap, fast, non-destructive, and environmentally conscious manner. In this study, 301 paddy soil samples from Fuyang, Zhejiang Province, China were used to explore the feasibility and effectiveness of XRF and vis–NIR spectra separately and in combination for estimating the soil Cr content. Two strategies, including outer-product analysis (OPA) and Granger–Ramanathan averaging (GRA), were used to combine the spectra and spectral models, respectively, from the two instruments (sensor fusion). Partial least-squares regression (PLSR) was used to train the models using a single sensor (XRF or vis-NIR spectra) and OPA fused spectra. Fifty boot straps were used to assess the uncertainty of the predictions for the aforementioned models. The results indicated that XRF spectra performed better than vis–NIR spectra for predictions of Cr content, with a Lin's concordance correlation coefficient (ρc) of 0.83, a root mean square error (RMSE) of 8.80, and a ratio of prediction derivation (RPD) of 1.75. Sensor fusion by OPA gave the highest prediction accuracy with a ρc of 0.90, RMSE of 6.80, and RPD of 2.30. The sensor fusion by GRA gave similar results with a ρc of 0.88, RMSE of 7.40, and RPD of 2.13. The predictions using both methods (OPA and GRA) were acceptable when considering the standard deviation of differences (SDD = 4.23). This suggests that OPA and the GRA sensor fusion methods are efficient and accurate for rapid measurement of Cr and provide a way forward for using these technologies for fast, sensor-based soil characterization.

Synthesis, structure and physico-chemical properties of two uranyl complexes of cucurbiturils mediated by sulfate ions

In this article, with the aid of additional ligands, (UO2)2(CB5)(SO4)2(H2O)2•5H2O ( U-CB5-SO 4 ) and (UO2)-(CB6)0.5(SO4)(H2O)•4H2O ( U-CB6-SO 4 ) were synthesized by hydrothermal method at high temperature. Their structures and physico-chemical properties were characterized by a combination of single-crystal X-ray diffraction, PXRD, TG-DSC, FTIR, UV-Vis and fluorescence spectra. U-CB5-SO 4 crystalized in orthorhombic system, and space group Pnma , while U-CB6-SO 4 crystalized in monoclinic system and space group I2/m . U-CB5-SO 4 forms a yellow windmill-like poly crystal, while U-CB6-SO 4 forms a yellow stick-like single crystal.

Effects of the type of biomass and ashing temperature on the properties of solid fuel ashes

Abstract Ashes were prepared by annealing selected types of solid fuels (biomass: corn cobs, sunflower husks, olive pomace, hay pellets and rice husks; coal: lignite and bituminous; and alternative fuel: paper sludge) at different temperatures (550°C, 815°C and 975°C). Based on X-ray fluorescence spectra, the slagging/fouling indexes were used to study the effects of the type of ash and the ashing temperature on the ash fouling and slagging properties. Slagging indexes were compared with the ash fusion temperatures. Ash fusion temperatures were measured by a LECO AF-700. The lowest deformation temperature (below 1000°C) was seen for the ashes prepared from hay pellets and corn cobs. On the other hand, the deformation temperature exceeded 1500°C for ashes prepared from paper sludge, sunflower husks and rice husks. By calculating the different slagging/fouling indexes, all the ashes exhibited slagging/fouling problems of varying degrees.

Study of zinc coating thickness gauge by Monte Carlo simulation

This paper introduces how to utilize the Monte Carlo N-Particle Transport Code (MCNP) in calculating the thickness of zinc coating which distributed homogeneously in an analyzed specimen. Experiments were performed on the specimens that made of 2 mm thickness steel substrates which covered by intermediate thickness (40-175 gm-2) zinc layer, with the purpose of analyzing the x-ray fluorescence spectra and comparing the changes of zinc fluorescence detection efficiency under different energy monochrome photons or different detector distance. The results show that when the energy of monochrome photons is equal to 10 keV as well as the distance of detector is equal to 4 cm, the fluorescence of zinc Kα has a very good linear relationship with the thickness of zinc coating. It indicates that the MCNP code can be applied for simulating the galvanizing thickness gauge. In addition, under the same other conditions, the experimental results were not affected by different incident spot sizes (0.01-1cm).

Effect of mechanical noise upon X-ray fluorescence analysis

The effect of the external mechanical noise on energy dispersive X-ray fluorescence (EDXRF) spectra has been investigated. A Nd2O3 sample was bombarded by the gamma-rays of 59.54 keV energy. The annular radioactive source (americium-241) with intensity equal to 1 Curie was used. The intensities of characteristic x-rays emitted from the Nd2O3 sample were measured using a high purity germanium detector. The mechanical noise applied to the experimental system had intensity values of 50 dB, 60 dB, 70 dB, 80 dB, 90 dB, and 100 dB. A sound level meter (Model 8928) was used to measure the external mechanical noise levels. The net area (P), background intensity (B), peak-to-background ratio (P/B), and full width at half-maximum (FWHM) of the characteristic peaks were determined in the energy dispersive X-ray fluorescence spectra obtained from Nd2O3 sample. It was observed that the background intensities of and peaks of the sample increased with the increasing mechanical noise level. The peak-to-background ratios (P/B) and the peak resolution decreased with increasing mechanical noise level.

Dual-mode conversion luminescent properties of PbF2:Er3+, Yb3+ phosphors

PbF2: Er[Formula: see text], Yb[Formula: see text] phosphors with the property of dual-mode conversion were prepared successfully by the high-temperature solid-state reaction method. The structure and luminescence properties of the samples were characterized by X-ray diffraction (XRD) and fluorescence spectrum method. The luminescence mechanisms of the samples under single ultraviolet (UV) or infrared (IR) light source excitation and UV[Formula: see text]IR co-excitation were analyzed. Under 376, 980 and 1550[Formula: see text]nm excitation, the phosphors showed intense green and red emission, the green emission (520–570[Formula: see text]nm) and the red emission (650–680[Formula: see text]nm) originated from the 2H[Formula: see text]I[Formula: see text], 4S[Formula: see text]I[Formula: see text] and 4F[Formula: see text]I[Formula: see text] transitions of Er[Formula: see text] ions, respectively. The fluorescence enhancement effect was observed in the UV and IR co-excited samples, which is derived from the infrared photon reabsorption of the ions at metastable energy levels.