Particle Induced X-ray Emission Measurements Research Articles

Historical pyrite “mirrors” from the Ecuadorian Cañari culture, digital microscopy observations, mineralogical and elemental analysis

This research relies on microscopy and digital microscopy observations and spectral analysis techniques: Raman spectroscopy, laser-induced breakdown spectroscopy (LIBS) and particle-induced X-ray emission (PIXE), to recover part of the lost identity of two pyrite (FeS2) cones. Conserved in Paris, at the Muséum National d'Histoire Naturelle (MNHN), the first one is registered MIN000-3519 in the collection of the mineralogist René-Just Haüy, the second one, registered 105.504, is a stray object. All information related to its origin would have been lost during the move (1837–1841) of the collections from the former Cabinet du Jardin du Roy to the new earth science gallery of the MNHN. Our historical research (Gendron, 2022) revealed that the first one, described as an “Inca mirror”, was shipped from Peru around 1760 by the botanist Joseph de Jussieu to his brothers Antoine and Bernard. They also confirmed that these two pyrite cones are archaeological objects of the Ecuadorian Cañari culture (500–1500 AD).Raman analyses conducted on the MIN000-3519 specimen confirm that it was developed on a quartz paragenesis. While the faces observation of no.105.504 reveals that the crystal used for its cut was triglyph twinned, a crystal which must have been cubic or dodecahedral pentagonal. The observation of the technical traces in digital microscopy makes it possible to reconstruct a process of similar cut for the two “mirrors” and help to discover red mineral clusters in the bottom of the crystalline gaps. LIBS analyses were also applied to get complementary information on in-depth element distribution, such as Fe and Al, in order to understand the stratigraphy inside the cracks. Finally, PIXE measurements do not confirm that these two pyrites come from the same deposit. But, this analytical technique is hampered by the nature of the element Fe which offers multiple and random bonding possibilities during the crystallization of iron minerals and by the lack of a comparative sample in the Parisian mineralogic collections.

Sub-band gap infrared absorption in Si implanted with Mg

Single-crystalline Mg-implanted Si layers are synthesized by ion implantation followed by pulsed laser melting. The Mg doping concentration is reaching 1021 cm−3. The Raman, Rutherford backscattering spectrometry/channeling and particle induced x-ray emission measurements confirm the recrystallization of the Mg-implanted Si layer. A strong below band gap infrared absorption over the wavelength range of 1.4–6.2 µm (0.2–0.87 eV, in the mid-infrared range) has been observed in the Mg-implanted Si layers. It is associated with deep levels induced by Mg atoms at high implantation level. This work points out the potential of Mg-implanted Si for room-temperature light detection in a broad infrared range for the new generation of Si-based photonics.

Comparing electrochemical analysis and particle induced X-ray emission measurements of Prussian Blue Analogue deposits

Prussian Blue Analogues are of major interest for their use in alternative battery technologies due to their charge storing ability with a long life cycle. In this work the Prussian Blue Analogue nickel hexacyanoferrate (Ni-HCF) was produced using an all electrochemical method. Creating charge storing materials with electrochemical processes provides a new approach to the development of battery-like materials. These methods have not been commonly employed because the charge storing material yield is not directly known. The charge storage of the Ni-HCF was characterized with two different methods which provided a measure of the electrochemically active Fe present. These were then compared with the Particle Induced X-ray Emission (PIXE) method which measured the total amount of Fe present. By comparing the electrochemical measurement of active Fe to the total Fe as measured by PIXE, the percentage of material that is active in the charge storage was determined. This enables an independent calculation of the specific charge capacity of the material for comparison to other battery technologies.

A trial application of particle-induced X-ray emission analysis to microplastic samples collected from the seashore

Here, we apply 20 MeV particle-induced X-ray emission (PIXE) to elemental analysis of microplastic samples with a diameter of approximately 2 mm, collected from the seashores of the northeastern area of Honshu in Japan. The samples were in a grain form with unwanted elements adhering to their surfaces. The PIXE measurements were conducted in a helium atmosphere. For normalization, the number of K X-rays of the residual gas argon was used instead of the directly measured beam irradiation, and the number of continuous X-rays in the PIXE spectrum was used instead of the mass of each sample. Thirteen elements were identified on the microplastics, among which were toxic chromium and lead. Thus, PIXE analysis is useful for analyzing microplastic samples.

Fast, asymmetric and nonhomogeneous clearance of SiC nanoaerosol assessed by micro-particle-induced x-ray emission.

To study the biopersistence of a silicon carbide(SiC) nanoaerosol in rat lungs, as time-dependent clearance and spatial distribution. Sprague-Dawley rats were exposed 6h/day during 5days to a SiC nanoaerosol at 4.91mg SiC/l. SiC biopersistence in rat lungs sections was assessed over 28days by micro-particle-induced x-ray emission (μPIXE) as 2D maps and by particle-induced x-ray emission (PIXE) for whole-lung quantification. 2D maps were analyzed for SiC spatial distribution as skewness and kurtosis. Half-time clearance was 10.9±0.9days, agreeing with PIXE measurements. Spatial-temporal analysis of SiC indicated decreased symmetry and homogeneity. Fast SiC clearance points that current nanoaerosol exposure may not be enough to trigger lung overload. Spatial distribution shows an asymmetric and nonhomogeneous SiC clearance.

Important role of the non-uniform Fe distribution for the ferromagnetism in group-IV-based ferromagnetic semiconductor GeFe

We investigate the growth-temperature dependence of the properties of the group-IV-based ferromagnetic semiconductor Ge1−xFex films (x = 6.5% and 10.5%), and reveal the correlation of the magnetic properties with the lattice constant, Curie temperature (TC), non-uniformity of Fe atoms, stacking-fault defects, and Fe-atom locations. While TC strongly depends on the growth temperature, we find a universal relationship between TC and the lattice constant, which does not depend on the Fe content x. By using the spatially resolved transmission-electron diffractions combined with the energy-dispersive X-ray spectroscopy, we find that the density of the stacking-fault defects and the non-uniformity of the Fe concentration are correlated with TC. Meanwhile, by using the channeling Rutherford backscattering and particle-induced X-ray emission measurements, we clarify that about 15% of the Fe atoms exist on the tetrahedral interstitial sites in the Ge0.935Fe0.065 lattice and that the substitutional Fe concentration is not correlated with TC. Considering these results, we conclude that the non-uniformity of the Fe concentration plays an important role in determining the ferromagnetic properties of GeFe.

Transition-Edge Sensors for Particle Induced X-ray Emission Measurements

In this paper we present a new measurement setup, where a transition-edge sensor detector array is used to detect X-rays in particle induced X-ray emission (PIXE) measurements with a 2 MeV proton beam. Transition-edge sensors offer orders of magnitude improvement in energy resolution compared to conventional silicon or germanium detectors, making it possible to recognize spectral lines in materials analysis that have previously been impossible to resolve, and to get chemical information from the elements. Our sensors are cooled to the operation temperature ( $$\sim $$ 65 mK) with a cryogen-free adiabatic demagnetization refrigerator, which houses a specially designed X-ray snout that has a vacuum tight window to couple in the radiation. For the best pixel, the measured instrumental energy resolution was 3.06 eV full width at half maximum at 5.9 keV. We discuss the current status of the project, benefits of transition-edge sensors when used in PIXE spectroscopy, and the results from the first measurements.

Analysis of blood serum of lung cancer patients using particle induced X-ray emission

Trace elemental imbalance in human beings is postulated to exert action, directly or indirectly, on the carcinogenic process. The objective of this study was to evaluate the levels of trace elements in blood serum samples of lung cancer patients and analyze their alteration with respect to healthy controls. Particle induced X-ray emission (PIXE), a well established method for elemental analysis, was used to identify and quantify trace elements in the blood serum samples of the studied groups. The PIXE measurements were carried out using 2.5 MeV collimated proton beam from the 3 MV Tandem Pelletron Accelerator at Ion Beam Laboratory, Institute of Physics, Bhubaneswar, India. The serum of the cancerous group displayed increased concentrations of Ti, Ni, and Cu but lowered concentrations of V, Cr, Mn, Fe, Co, Zn, and Se. Statistically significant differences were found for serum Cr (p < 0.01), Fe (p < 0.0005), Ni (p < 0.05), Cu (p < 0.00005), and Zn (p < 0.0005) between the two studied groups. The copper to zinc ratio for the lung cancer group was 2.24 ± 0.39, which was almost three times the value for normal subjects (0.77 ± 0.14). The observed alterations are discussed with respect to the possible mechanisms by which these elements might influence the carcinogenic process. Significant reduction in mortality from lung cancer can be achieved by advances in early diagnosis and implementation of multidisciplinary treatment programmes leading to improvement of survivorship and better quality of life. It is expected that similar studies from all corners of the world would ultimately lead to the development of novel therapeutic agents to treat lung cancer.

Analysis of trace elements in blood sera of breast cancer patients by particle induced X-ray emission

Trace elemental imbalance in human beings is postulated to exert action, directly or indirectly, on the carcinogenic process. The objective of this study was to evaluate the levels of trace elements in blood sera of breast cancer patients and analyze their alteration with respect to healthy controls. This work was also intended to establish the role played by the trace elements in carcinogenic process. Particle induced X-ray emission (PIXE) technique was used for trace elemental analysis of blood sera of breast cancer patients and healthy controls. The PIXE measurements were carried out using a 2.5 MeV collimated proton beam from the 3 MV Tandem Pelletron accelerator at Institute of Physics, Bhubaneswar, India. On comparing the trace elemental content in the sera of breast cancer patients with those of control subjects, significant variations were observed in the levels of most of the trace elements. The serum levels of almost all the elements except Fe and Cu were observed to be depressed in cancer patients with respect to normal subjects. However, this variation was significant only for Ti (P < 0.00005), Cr (P < 0.005), Mn (P < 0.0005), Ni (P < 0.01), Zn (P < 0.000001), and Se (P < 0.05). On the other hand, significant elevations were observed in serum Fe (P < 0.05) and Cu (P < 0.005) levels in cancer patients. The findings presented in this paper give guidelines for future study into the possible roles and interactions of essential trace elements in the breast carcinogenic process.

In vitro evidence of dysregulation of blood–brain barrier function after acute and repeated/long-term exposure to TiO 2 nanoparticles

The effects of titanium dioxide nanoparticles (TiO 2 NPs) on blood–brain barrier (BBB) function are unknown. Here, we report such evidence of adverse effects after in vitro exposure of a rat primary cell-based BBB model to NPs. BBB integrity was studied by measuring the flux of sucrose through the monolayer. P-glycoprotein (P-gp) activity was assessed by measuring the passage of vinblastine. Transcription profiles of P-gp and other ABC transporters as well as of cytokines were investigated by real-time PCR. Electron microscopy and particle-induced X-ray emission measurements were performed. We compared several exposure modalities, from early to chronic, mimicking a brain-to-blood transport or a systemic contamination. In the first case, BBB integrity was preserved, but P-gp activity of endothelial cells (BECs) was reduced. In the second case, BBB integrity and P-gp function were impaired from 5 μg/mL for 24 h and expression of tight junction proteins and efflux transporters was modulated. An inflammatory response had repercussions on ABC transporter expression of glial cells. We demonstrate that NPs accumulated in BECs and crossed the cell monolayer. These findings suggest that there is an immunoregulatory loop between inflammatory components, BECs and glial cells in the dysfunction of the BBB during exposure to TiO 2 NPs.

On the structured imperfections of bulk GaSb using high resolution transmission electron microscopy

GaSb is a promising III–V direct band gap semiconductor with sphalerite type FCC structure. Its band gap value has made it an excellent candidate for the conversion of infrared radiation to electricity. The wafers of GaSb, that were studied, originated from ingots grown with the Liquid Encapsulated Chochralski method. In all cases, Energy Dispersive X-ray Spectroscopy and Particle Induced X-ray Emission measurements demonstrated an excess of Sb. In the present work conventional transmission electron microscopy (CTEM) and high resolution electron microscopy (HRTEM) were used in order to determine the effect of the Sb excess in the structural characteristics of the material, mainly after thermal treatment. A structure model based on the ordering of the Sb antisites (Sb Ga) rather than the Ga vacancies (V Ga) is proposed for the observed modulation in small areas of the material.

Electrical and magnetic properties of RE-doped ZnO thin films (RE = Gd, Nd)

Abstract Due to the small magnetic moments observed for 3d transition metals in ZnO [M. Diaconu, H. Schmidt, H. Hochmuth, M. Lorenz, G. Benndorf, J. Lenzner, D. Spemann, A. Setzer, K.W. Nielsen, P. Esquinazi, M. Grundmann, Thin Solid Films 486 (2005) 117], there is still space for optimizing ZnO-based diluted magnetic semiconductors for spintronics applications. Motivated by the observation of magnetic moments as high as 4000μB/Gd atom in GaN:Gd [S. Dhar, O. Brandt, M. Ramsteiner, V.F. Sapega, K.H. Ploog, Phys. Rev. Lett. 96 (2005) 037205], we investigated ZnO films doped with 0.01, 0.1 or 1 at.% rare earth (RE) metals. The films, with thicknesses between 20 nm and 1 μm, have been grown by pulsed laser deposition on a -plane sapphire or fused silica substrates. The homogenous incorporation of the RE ions in ZnO was investigated by combined Rutherford backscattering and particle induced X-ray emission measurements. Hall measurements revealed an unexpected dependence of the electron concentration on film thickness, proving a non-uniform distribution of electrically active defects. Magnetotransport measurements at different temperatures were performed to study the magnetoresistance and the presence of the anomalous Hall effect. Large negative magnetoresistance was obtained at 5 K, while no anomalous Hall effect was observed. These results indicate that there are no exchange interactions between the RE ions.

PIXE analysis of some medicinal plants used in cleaning teeth in southwestern Nigeria

Sixteen medicinal plants used for cleaning teeth in southwestern Nigeria were analyzed using the particle-induced X-ray emission (PIXE) technique. These medicinal plants have other therapeutic uses, but the emphasis and main focus were on their beneficial effects on human teeth. PIXE measurements were carried out using 1.8 MeV collimated proton beam from the 2.5 MV AN 2000 Van de Graaff accelerator at the Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro, Padova Italy. The results showed the presence of 18 different elements at different concentrations, 2 plants had traces of gold, and none of the plants contained any toxic heavy metals. The metabolic roles of the detected elements were discussed especially as they affected the formation, growth, development, and protection of human teeth. The results of this study are presented and discussed.

RBS/PIXE channeling for InAlGaN epitaxial layers

Characteristics of InAlGaN quaternary alloy epitaxial layers have for the first time been studied by Rutherford backscattering spectrometry (RBS) and particle induced X-ray emission (PIXE). We have evaluated the crystalline quality from the normalized yield as a function of aluminium content of the InAlGaN quaternary alloy epitaxial layers with the same indium content. The compositions of the samples were estimated to be In0.02Al0.12Ga0.86N and In0.02Al0.24Ga0.74N from RBS measurements. The normalized yield for an In0.02Al0.12Ga0.86N epitaxial layer and an In0.02Al0.24Ga0.74 epitaxial layer was calculated to be 2.44% and 4.20%, respectively. This indicates that they have excellent crystalline quality and that the crystalline quality of the epitaxial layer becomes worse with increase of the aluminum content. PIXE channeling has also been performed for both samples. Individual signals of indium and aluminum atoms in InAlGaN epitaxial layers were obtained by PIXE measurements. The normalized yield of the indium was smaller than that of the aluminum in both InAlGaN epitaxial layers which suggest the differences of their lattice vibration or atomic displacements.

Quantification of arsenic in activated carbon using particle induced X-ray emission

To date, the trace elemental analysis of solids with inhomogeneous internal structure has been limited, particularly in the case of adsorbents. High-energy ion beam based particle induced X-ray emission (PIXE) is an ideal analytical tool suitable for simultaneous quantification of trace elements with high accuracy. In this study, PIXE was used to quantify arsenic in the adsorbents, granular activated carbon (GAC) and powder activated carbon (PAC). Pelletized and unmodified GAC and PAC samples were analyzed along with powder samples deposited on thin teflon filters. These sample preparation methods resulted in samples of various thicknesses and densities. PIXE measurements taken from these samples were compared to results from neutron activation analysis (NAA) and atomic absorption spectroscopy (AAS). There is a good agreement between the values from the NAA and pelletized PIXE measurements and some AAS measurements.

Evaluation of Nigerian Animal Feeds by Particle-Induced X-Ray Emission

There is need to evaluate the locally available animal feeds in Nigeria so as to be able to combine them in acceptable proportions to the animals to achieve the desired growth rate. The technique of particle-induced X-ray emission (PIXE) was employed for the evaluation of these locally available animal feeds, which include Panicum maximum (Guinea grass), Cynodon plectostachyum (grass), Leucaena leucephala (legume), Calopogonium mucunoides (legume), Gliricidia sepium (legume), Euphorbia polychrome (legume), Pueraria phaseloides (legume), and Centrosema pubescens (legume). The proton beam delivered by the 2.5-MV AN 2,000 Van de Graaff accelerator at the International Centre for Theoretical Physics Laboratori Nazionali di Legnaro (LNL), Padova, Italy was used for the PIXE measurements. Twenty-one different elements were detected at various concentrations and their nutritional effects on different animals are discussed.

Elemental composition (Si, Fe, Ti) of atmospheric dust over the last 220 kyr from the EPICA ice core (Dome C, Antarctica)

AbstractIn this work, we present the records of insoluble silicon (Si), iron (Fe) and titanium (Ti) from continental mineral particles (dust) archived in the first 2200m of the EPICA Dome C (EDC) ice core. More than 200 samples covering the last 220 kyr, back to marine isotopic stage 7.4, were analyzed using the particle-induced X-ray emission (PIXE) technique, applied here for the first time to the investigation of the mineral content of an Antarctic ice core. The measurements were made exclusively on the insoluble fraction, obtained from filtration of the melted ice samples. The mineral fraction of the particle mass determined from the PIXE measurements is highly correlated to the total dust mass determined by particle counting using a Coulter©Counter. The principal variations during the different climatic periods are very coherent between the PIXE analysis results and the total dust mass determined by counting. Both sets of results show increasing concentration values during glacial stages 2, 4 and 6 and very low particle content during interglacials (Holocene and stage 5e). The large increase in atmospheric dustiness during cold stages is assumed to be caused by several factors, among which are the enhanced vigour of atmospheric transport. However, the PIXE results from this work highlight some slight differences in Si, Fe and Ti concentrations with respect to the total dust mass during the different climatic periods. As a hypothesis, such variations could reflect either different atmospheric processes affecting particles during transport, or changes that occurred in the dust source regions.

Non-destructive depth profiling of solid samples by atomic and nuclear interactions induced by charged particles

The study of complex materials (non-homogeneous matrices containing medium and/or heavy atoms as major elements) by Particle Induced X-Ray Emission (PIXE) requires the tailoring of the experimental set up to take into account the high X-ray intensity produced by these main elements present at the surface, as well as the expected low intensity from other elements “buried” in the substrate. The determination of traces is therefore limited and the minimum detection limit is generally higher by at least two orders of magnitude in comparison with those achievable for low Z matrices ( Z≤20). Additionally, those high Z matrices, having a high absorption capability, are not always homogeneous. The non-homogeneity may be, on the one hand, a layered structure (which is uneasy to profile by Rutherford Backscattering Spectroscopy (RBS) if the material contains elements of neighbouring atomic masses or if the layered structure extends on several microns). PIXE measurements at various incident energies (and with various projectiles (p, d, He 3, He 4)) are an alternative method to overcome those difficulties. The use of special filters to selectively decrease the intensity of the most intense X-ray lines, the accurate calculation of the characteristic X-ray intensity ratios (Kα/Kβ, Lα/Lβ) of individual elements, the computation of the secondary X-ray fluorescence induced in thick targets are amongst the most important parameters to be investigated in order to solve these analytical problems. Examples of Al, Si, Cu, Ag, Au based alloys as encountered in industrial and archaeological metallurgy are discussed. The non-destructive aspect of the ion beam techniques is proved by applying the method in vivo for the study of fluorine migration in tooth enamel. Preliminary results on the composition of the blocks of the pyramid of Cheops are presented in the scope of a complete revision of the procedure of its construction.

PIXE AND NAA ANALYSIS OF MERCURY IN A STANDARD SET OF SOUTHERN MAGNOLIA WOOD SAMPLES

Several southern magnolia (magnolia grandiflora) tree samples, with known concentrations of mercury, were analyzed using particle induced x-ray emission (PIXE) and neutron activation analysis (NAA). Results from the PIXE measurements indicate that the average mercury absorption percentage was found to be 85 ± 4%. The distribution of mercury was found to be reasonably homogeneous over the sample surface. However, small variations in mercury concentration are most likely caused by the structure of cellulose in the wood. Mercury in the samples appears to be stable to a total integrated charge of 10 μC. Three mercury L-shell x-rays are easily observed in the resulting PIXE spectrum. Using PIXE, the mercury detection limit was calculated to be approximately 1 ppm. With one exception, the measured NAA mercury concentrations were larger than the corresponding mass-based values. The NAA mercury detection limit for the southern magnolia samples was estimated to be about 0.017 ppm (17 ppb).

The distribution of InCl x compounds in model polymeric LEDs: A combined low and high-energy ion beam analysis study

A combination of low- and high-energy ion beam analysis techniques was used to determine the distribution of indium chloride compounds in model polymeric light-emitting diodes (p-LEDs). Parts of polymeric LEDs (polydialkoxyphenylenevinylene (OC 1C 10-PPV) on indium-tin-oxide (ITO) substrates) were exposed to a HCl/Ar flow to simulate the processes occurring during conversion of precursor PPVs and acid treatment of polymers. Samples with variable exposure times as well as pristine samples were studied with Rutherford backscattering spectrometry (RBS), low energy ion scattering (LEIS), X-ray photoelectron spectroscopy (XPS) and particle induced X-ray emission (PIXE). The RBS measurements show that after HCl exposure indium is distributed throughout the OC 1C 10-PPV layer. LEIS and XPS measurements indicate that the indium and chlorine are present at the outermost surface of the OC 1C 10-PPV layer. PIXE measurements in combination with the RBS data demonstrate that the indium chloride in the OC 1C 10-PPV layer is distributed in blisters (∅=50 μm) which are orientated perpendicular to the sample surface. To study the OC 1C 10-PPV/ITO interface, samples were delaminated by peeling the polymeric layer of the ITO using Scotch tape. LEIS measurements on the fracture planes demonstrate the formation of an interfacial layer between the ITO and the PPV. The implications for p-LEDs are discussed.