Particle Induced X-ray Emission Spectra Research Articles

ELEMENTAL ANALYSIS OF MARINE CORE SEDIMENT BELONG TO CENTRAL WESTERN BAY OF BENGAL BY USING PIXE

The aim of the present work is to estimate the accumulation of various elements related to the core sediment belong to the Krishna-Godavari marginal area with a nuclear analytical technique. Hence, a 4.12 m long marine sediment gravity core was collected from near to Nizampatnam Bay that related to Bay of Bengal and by using particle induced X-ray emission (PIXE) elemental concentrations have been determined. The concentrations of major elements like Fe, Ca, K, Ti, Mn and minor (trace) elements such as Sr, Co, V, Zn, Ni, Cu, Rb, Sc and Cr have been evaluated with the obtained PIXE spectra. These values are interpreted based on the monsoonal runoff coming from the rivers causing to play an important role for bring lot of sedimentary material of the coastal waters to the Bay of Bengal. Further results are interpreted to understand biological and anthropogenic activities, chemical reactions etc during Holocene and Pleistocene periods.

RBSandPIXEdata analysis by two dimensional correlation mapping techniques: On the effects of ion irradiation and sulfonation on poly(ether ether ketone) membranes

The present work proposes the use of two‐dimensional correlation mapping (2D‐CM) methods to analyze both particle induced X‐ray emission (PIXE) and Rutherford back scattering (RBS) spectra. RBS spectra of ion irradiated (H+and He2+) poly(ether ether ketone) (PEEK) films were analyzed by both generalized and hybrid 2D‐CM techniques to reveal the chemistry involved in different ion irradiation types. The analysis indicated different irradiation mechanisms using He2+and H+high energy ion beams and was assigned to X‐linking and Y‐linking, respectively. The effects of sulfonation on the structure of PEEK membranes were also analyzed from their RBS and PIXE spectra. The sequential order of elemental concentration change with increasing the degree of sulfonation (DS) was determined as: N→S→O→C, and the origin of Nitrogen was assigned to the casting solvent as revealed from nuclear magnetic resonance (NMR) spectra. In addition, Hetro‐2D‐CM‐PIXE‐RBS analysis indicated the presence of three RBS Sulfur signals, and were assigned to Sulfur at surface, in the middle and in depth. 2D‐CM techniques could be considered as a promising approach to enrich information obtained by ion beam analysis.

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.

Ion beam analysis of Cu(In,Ga)Se2 thin film solar cells

The present work investigates the potential of ion beam analysis (IBA) techniques such as the Rutherford backscattering spectrometry (RBS) and particle induced X-ray emission (PIXE) using helium ions to provide quantitative in-depth elemental analysis of various types of Cu(In,Ga)Se2 thin films. These films with a thickness of about 2μm are used as absorber layers in photovoltaic devices with continuously increasing the performance of this technology. The preparation process generally aims to obtain an in-depth gradient of In and Ga concentrations that optimizes the optoelectronic and electrical properties of the solar cell. The measurements were performed at directly accessible single or double layered CIGS absorbers and at buried absorbers in completed thin film solar cells. The IBA data were analyzed simultaneously in order to derive best fitted profiles that match all experimental RBS and PIXE spectra. For some samples elemental profiles deduced form synchrotron based, reference free grazing incidence X-ray fluorescence analysis were compared with the IBA results and an overall good agreement was observed within quoted uncertainties.

Self-consistent depth profiling and imaging of GaN-based transistors using ion microbeams

Using an ion microprobe, a comprehensive lateral and in-depth characterization of a single GaN-based high electron mobility transistor is carried out by means of Rutherford backscattering spectrometry (RBS) in combination with particle induced X-ray emission (PIXE). Elemental distribution was obtained for every individual section of the device (wafer, gate and source contact), identifying the basic constituents of the transistor (including the detection of the passivant layer) and checking its homogeneity. A self-consistent analysis of each individual regions of the transistor was carried out with a simultaneous fit of RBS and PIXE spectra with two different beam conditions. Following this approach, the quantification of the atomic content and the layer thicknesses was successfully achieved overcoming the mass-depth ambiguity of certain elements.

Ferromagnetism on the unpolished surfaces of single crystal metal oxide substrates

It is shown that a variety of single crystal substrates (Al2O3, LaAlO3, SrTiO3, TiO2, and ZnO), purchased from commercial suppliers, contain a ferromagnetic component to the magnetization in addition to the expected linear magnetic response. This ferromagnetic contribution is only observed on the unpolished surfaces and can be eliminated by either polishing or annealing at 600 °C in air, but not by annealing at 600 °C in a vacuum of 5 × 10−6 Torr. Particle induced x-ray emission spectra demonstrate that there is excess Fe on the unpolished surfaces of these single crystal substrates. While defect related ferromagnetic signals have been reported in some of these substrates, and while our results do not exclude this origin of ferromagnetism, we clearly show that the ferromagnetic signals observed in our samples are largely due to excess iron on the unpolished surfaces, possibly in the form of a mixture of Fe, Fe3O4, and or γ-Fe2O3.

PARTICLE‐INDUCED X‐RAY EMISSION (PIXE) ANALYSIS OF OBSIDIAN FROM TEOTIHUACAN

A collection of 50 archaeological obsidian samples studied in the framework of the Preciudadela Project (Teotihuacan, Mexico) has been analysed using particle‐induced X‐ray emission (PIXE) with the external beam line of the Accélérateur Grand Louvre d'Analyse Elémentaire facility (C2RMF, Paris) and of the Instituto de Física (UNAM, Mexico). This work addresses the provenance of these obsidian samples, with the purpose of determining if they come from the obsidian sources exploited by Teotihuacans (mainly Otumba and Sierra de Pachuca), from other sources, or arrived via commercial exchanges with other regions. For that, the elemental compositions derived from the PIXE spectra have been compared with data published in the literature on the basis of instrumental neutron activation analysis. From the concentrations of selected key elements (Na, K, Mn, Fe, Zn, Rb, Sr, Zr), it was possible to unambiguously assign the provenance of most samples. Many originate from two major sources, namely Sierra de Pachuca (Hidalgo) and Otumba (Mexico), which were the main obsidian deposits used by the Teotihuacans. However, some samples exhibit a compositional fingerprint matching other provenances, i.e., Paredón (Puebla) and Zacualtipan (Hidalgo).

Characterisation of hot particles remaining in soils from Palomares (Spain) using a nuclear microprobe

More than 40 years ago, an aircraft accident took place in Palomares (Spain) which involved the destruction of two nuclear weapons. A portion of the remaining transuranic contamination in the affected soils is present in the form of small high activity concentration particles (10–100 μm), also called “hot particles”, which contain plutonium and uranium. Several hot particles have been isolated and identified from the superficial soils recently collected in the zone affected by the accident. The isolation was carried out by screening the soil using gamma-ray spectrometry, through discrimination of the high activity concentrations of 241Am in the samples which indicates the presence of plutonium. The hot particles, composed of several elements with very high atomic number, could be easily identified by scanning electron microscopy (SEM) in backscattering electron image (BSE) mode. Moreover, their morphology and size were also studied using SEM in secondary electron (SE) mode. In this work, the hot particles have been investigated with the nuclear microprobe of the National Accelerator Centre (CNA) in Seville. Compositional analysis, mapping and depth distribution of different elements have been performed by a simultaneous combination of Particle Induced X-ray Emission (PIXE) and Rutherford Backscattering Spectrometry (RBS). Uranium and plutonium have been identified in the PIXE spectra as the main components of the particles, whereas the concentration of Americium is two orders of magnitude smaller. In addition, an estimation of the particles density has been obtained by comparison of the RBS results with the particles thickness directly determined by SEM.

Structural analysis of (Ga,Mn)N epilayers and self-organized dots using MeV ion channeling

Rutherford backscattering (RBS) and particle-induced X-ray emission (PIXE) experiments were performed on (Ga,Mn)N epilayers and self-organized dots grown by plasma-assisted MBE. The combined channeling RBS and Mn PIXE experiments were performed on Ga 0.949 M 0.051 N epilayer, which was confirmed to be of pure diluted phase by X-ray diffraction (XRD) in our previous study, in order to check the presence of Mn atoms in the interstitial site in wurtzite crystal. The axis scan around and axes and the plane scan around (1010) plane revealed that almost all the Mn atoms were in the substitutional site of wurtzite GaN crystal. For self-organized dots of (Ga,Mn)N grown on AlN by MBE, the PIXE spectra were measured and the Mn composition in the dot layer was estimated from the ratio of emission intensity of Mn and Ga K α lines. At a result, it was found that the Mn composition in the dots was higher by two or three times than that in thick epilayers grown with the addition of the same amount of Mn flux.

Background estimation in experimental spectra

A general probabilistic technique for estimating background contributions to measured spectra is presented. A Bayesian model is used to capture the defining characteristics of the problem, namely, that the background is smoother than the signal. The signal is allowed to have positive and/or negative components. The background is represented in terms of a cubic spline basis. A variable degree of smoothness of the background is attained by allowing the number of knots and the knot positions to be adaptively chosen on the basis of the data. The fully Bayesian approach taken provides a natural way to handle knot adaptivity and allows uncertainties in the background to be estimated. Our technique is demonstrated on a particle induced x-ray emission spectrum from a geological sample and an Auger spectrum from iron, which contains signals with both positive and negative components.

Signal and background separation.

In many areas of research the measured spectra consist of a collection of "peaks"--the sought-for signals--which sit on top of an unknown background. The subtraction of the background in a spectrum has been the subject of many investigations and different techniques, varying from filtering to fitting polynomial functions, have been developed. These techniques yield results that are not always satisfactory and often even misleading. Based upon the rules of probability theory, we derive a formalism to separate the background from the signal part of a spectrum in a rigorous and self-consistent manner. We compare the results of the probabilistic approach to those obtained by two commonly used methods in an analysis of particle induced x-ray emission spectra.

HIGH RESOLUTION PIXE INSTRUMENTATION SURVEY, PART IV

In this review (in continuations) X-ray crystal spectrometers working on ion beams and their applications are surveyed. The present fourth part continues to describe: (i) their use for elemental analysis; (ii) their use for obtaining the information about the chemical effects in the Particle Induced X-ray Emission spectra; (iii) their use in basic research for obtaining information applied in the above relations and their applications on acelerators. We update the data of formerly discussed systems according to the changes in the world.

A PIXE study of clouded plagioclase from southern Sweden

Clouded plagioclase is found in mafic dykes occurring along the Protogine Zone in southern Sweden. The clouding intensity varies from slight to more pronounced brown/dark or opaque. In order to understand the trace-element partition/contribution in the clouding process, a PIXE (Particle Induced X-ray Emission) analysis has been conducted on clouded plagioclase samples (Bjära, Bjärnum, Taberg). The experiments were undertaken at the Lund Nuclear Microprobe. For each locality, PIXE spectra and elemental distribution line-profiles (rim to core) are displayed. This study has shown undulated (inhomogeneous), stepwise (semi-homogeneous), and homogeneous clouding at the elemental level. The result suggests that the trace elements partially contribute to the observed plagioclase clouding.

Influence of sample charging on satellite spectra during particle induced X-ray emission analysis

We demonstrate how the fine structures of particle induced X-ray emission spectra are influenced by build up of charge in insulating materials. We have measured silicon Kα satellite spectra emitted from fused quartz (SiO 2) that had been bombarded with 1.5 MeV He + ions under various conditions of electron shower. For the insulating fused quartz, the diagram line ( KL 0) appears much stronger than the KL n multiple-vacancy satellites ( n ⩾ 1) making the satellites difficult to discern. However, when an electron shower is applied to the fused quartz, the diagram line is lowered according to shower conditions and the KL 1, KL 2 and KL 3 satellites appear prominently. Emission of a strong diagram line from insulating fused quartz is principally due to the charging of the sample and its subsequent discharge.

ELEMENTAL ANALYSIS OF MOUSE HAIR BY PIXE METHOD

Constitutional elements of head hair of mouse (Mus musculus) were investigated by Particle-Induced X-ray Emission (PIXE) analysis. The high peaks of S, K and Ca, and the low peaks of several other elements were observed in PIXE spectra of all the specimens from the used strains. The result clearly indicates that the ratios of these elemental contents are different among the coat colors of mice. Further, we observed strain difference even in the same color.

Irradiation effect of rare-gas ions in type 304 austenitic stainless steel

Ar, Kr and Xe rare-gas ions were irradiated in foil specimens of type 304 stainless steel. An irradiation effect in the surface region of the foil specimens has been investigated by means of glancing angle X-ray diffraction (GXRD), Rutherford backscattering (RBS) and particle-induced X-ray emission (PIXE) in order to observe the retained rare-gas atoms and elucidate their correlation with the ion-induced martensitic phase transformation of γ phase → α phase. It has been seen that the amounts of Ar, Kr and Xe retained in stainless steel as estimated from PIXE spectra were affected by the sputtering under ion irradiation. It has been shown by GXRD measurements that the retained rare-gas atoms agglomerated and formed a highly-pressurized solid phase inclusion. It is clear from GXRD measurements that the amount of the phase transformation at saturation increased linearly with increasing ion range of the implanted rare-gas atoms irrespective of the ion species. We speculate from this linearity that the depth distribution of the ion-induced martensitic phase may overlap with that of the rare-gas inclusion in stainless steel, and the formation of the rare-gas inclusion has stress-induced the phase transformation of γ → α. However, before saturation of the ion-induced phase transformation, the degree of the phase transformation in stainless steel as estimated from the amount of retained rare-gas atoms clearly differed for the different ion species.

A new on-demand beam excitation system used in PIXE

By using a symmetrical driving method of electrostatic deflecting field, a new all-transistorized on-demand beam pulsing system for Particle-Induced x-ray Emission (PIXE) analysis has been made. The measured rise time of the electrostatic field is less than 35ns; the pile-up continuum in PIXE spectrum is greatly suppressed, and the counting rate reaches as high as 20,000 counts per second.

Rapid non-destructive determination of thin films of platinum by particle back-scattering

Rutherford back-scattering of α-particles is used to determine trace amounts of thin films of platinum. The method is sensitive to 0.3 ng of platinum and the response is linear from at least 0.01 to 80 μg Pt cm -2 of substrate surface area. Calibration with weighed standards reveals good accuracy and precision throughout the linear range. Up to at least 80 μg cm -2, no matrix effects can be observed for platinum determinations on Mylar, carbon, glass, and glass or quartz coated with up to 0.5 μm thicknesses of tin oxide. Particle-induced x-ray emission spectra are included to show their utility in surface composition analysis. The analytical procedure for the determination of platinum is rapid and non-destructive, and requires minimal sample preparation.