Application Of Particle Induced X-ray Emission Research Articles

Hair elemental analysis for forensic science using nuclear and related analytical methods

In this review, we explore determination of element contents in hair with neutron activation analysis (NAA) and particle induced X-ray emission (PIXE). Here we discuss factors that influence the accuracy and credibility of results, and conclusions drawn for forensic science. Hair structure, growth phase, deposition of trace elements in hair, sampling and washing procedures are important factors before analysis, whereas the availability of reference values or ranges of hair elemental composition for non-exposed populations, and toxicological considerations are vitally important for results interpretation. We present here selected applications of NAA and PIXE for testing hypothesis of criminal poisoning with toxic elements. In conclusion, we would like to emphasize the importance of future NAA and PIXE applications for accurate determination of toxic elements and for spatially resolved element contents in hair, respectively.

L X-ray emission induced by heavy ions

Particle-induced X-ray emission (PIXE) technique is usually applied using typically 1MeV to 3MeV protons or helium ions, for which the ion-atom interaction is dominated by the single ionization process. For heavier ions the multiple ionization plays an increasingly important role and this process can influence substantially both the X-ray spectra and atomic decay rates. Additionally, the subshell coupling effects are important for the L- and M-shells ionized by heavy ions. Here we discuss the main features of the X-ray emission induced by heavy ions which are important for PIXE applications, namely, the effects of X-ray line shifts and broadening, vacancy rearrangement and change of the fluorescence and Coster–Kronig yields in multiple ionized atoms. These effects are illustrated here by the results of the measurements of L X-ray emission from heavy atoms bombarded by 6MeV to 36MeV Si ions, which were reported earlier. The strong L-subshell coupling effects are observed, in particular L2-subshell, which can be accounted for within the coupling subshell model (CSM) developed within the semiclassical approximation. Finally, the prospects to use heavy ions in PIXE analysis are discussed.

PIXE analyses of polished otoliths for identification of anadromous whitefish in the Baltic Sea

In this work we describe an application of particle-induced X-ray emission (PIXE) to the elemental analysis of polished otoliths of whitefish. Two spots on polished otoliths were irradiated; one spot in the core region of the otolith and another one close to the edge. The irradiations were performed in air with a collimated 0.5mm proton beam. The ratio of the strontium concentrations in the two spots was used to distinguish between different ecotypes (river, sea, lake) of whitefish. Criteria on the ratios were suggested for identification of the whitefish forms. The results were compared to results of μ-beam PIXE scans as well as multi-point scans with the 0.5mm proton beam. The measuring set-up and the results are discussed.

Detection of halogenated flame retardants in polyurethane foam by particle induced X-ray emission

A novel application of particle-induced X-ray emission (PIXE) has been developed to detect the presence of chlorinated and brominated flame retardant chemicals in polyurethane foams. Traditional Gas Chromatography–Mass Spectrometry (GC–MS) methods for the detection and identification of halogenated flame retardants in foams require extensive sample preparation and data acquisition time. The elemental analysis of the halogens in polyurethane foam performed by PIXE offers the opportunity to identify the presence of halogenated flame retardants in a fraction of the time and sample preparation cost. Through comparative GC–MS and PIXE analysis of 215 foam samples, excellent agreement between the two methods was obtained. These results suggest that PIXE could be an ideal rapid screening method for the presence of chlorinated and brominated flame retardants in polyurethane foams.

Application of particle-induced X-ray emission, backscattering spectrometry and scanning electron microscopy in the evaluation of orthodontic materials

The focus of this investigation was on orthodontic materials used in the manufacture of dental brackets. The properties of these dental materials are subjected to various physical parameters such as elongation, yield strength and elasticity that justify their application. In turn, these parameters depend on the quantitative elemental concentration distribution (QECD) in the materials used in the manufacture. For compositional analysis, proton-induced X-ray emission (PIXE), backscatter spectrometry (BS) and scanning electron microscopy (SEM) were applied. QECD analysis was performed to correlate the physical parameters with the composition and to quantify imperfections in the materials. PIXE and BS analyses were performed simultaneously with a 3 MeV proton beam while electrons accelerated at 25 keV were used for the SEM analysis. From the QECDs it was observed that: (1) the major elements Cr, Fe and Ni were homogeneously distributed in the orthodontic plate; (2) the distribution of Mo and O correlated with one another; (3) there was a spread of Cr around regions of high C concentration; and, (4) areas of high concentrations of Mo and O corresponded to a decrease in C concentrations. Elemental concentration correlations are shown to indicate the similarities and differences in the ease of formation of phases, based on the tangent of linearity.

Ion-beam analysis for cultural heritage on the AGLAE facility: impact of PIXE/RBS combination

The combination of particle-induced X-ray emission (PIXE) and Rutherford backscattering (RBS) is particularly fruitful for the study of cultural heritage objects. Several set-ups have been developed at the AGLAE facility of the Louvre Laboratory to implement these techniques with an external beam. Successively have been tested the simultaneous use of PIXE and RBS with a single beam of protons, the sequential application of PIXE with protons and RBS with 4He2+ ions and finally the simultaneous implementation of PIXE and RBS with high-energy 4He2+ ions. Several examples illustrate the benefits of these combinations of techniques.

MEDICAL APPLICATIONS OF PARTICLE-INDUCED X-RAY EMISSION

We report two medical applications of particle-induced X-ray emission (PIXE) as described below (1) Observation of biological events: The kinetics of trace elements during the initiation of radiation-induced apoptosis (RIA) was observed using a micro-PIXE and PIXE. RIA is a process in which irradiated cells commit suicide; it results in the removal of severely damaged and harmful cells. During RIA, cytochrome c is released from the mitochondria and reaches the nucleus, where it activates a Ca- or Mg-dependent endonuclease. We examined this phenomenon by using a micro-PIXE and PIXE. A high concentration of Fe was detected in the stroma of cells in the early apoptotic phase. We also observed accumulation of large amounts of Ca and Mg in the nucleus.(2) Development of liquid-core microcapsules for novel cancer chemoradiotherapy: Currently, we are developing liquid-core (containing an anticancer drug) microcapsules that release their core content upon irradiation. These microcapsules will localize the anticancer drug within the irradiated field. The outer shell of these microcapsules is prepared from alginate and hyaluronic acid and polymerized by Fe, while the anticancer drug Paraplatin®(carboplatin) containing Pt is the liquid core. The micro-PIXE revealed that these microcapsules released their core content after irradiation, and the amount of carboplatin released was measured by PIXE. More than 83.1% ± 8.3% of the microcapsules were ruptured, and the amount of carboplatin released was more than 81.2% ± 2.3%. Thus, the combination of radiotherapy and chemotherapy showed improved antitumor effects and a decrease in adverse effects because of drug localization.

Chemical composition of a yellowish rainfall by the application of PIXE and micro-PIXE technique

Information of the chemical properties of rain fallen during the Asian dust (AD) event will help us to better understand the wet scavenging processes of dust particles. In this study, the chemical characteristics of rainwater and individual raindrops fallen during the AD storm have been investigated. The yellowish rainwater and individual raindrops were collected simultaneously in Kyoto, Japan on 7 April 2001. Particle induced X-ray emission (PIXE) was employed in the determination of chemical properties of soluble and insoluble fractions of rainwater. In addition, micro-PIXE was applied to the chemical analysis of residual materials retained in the initial individual raindrops. The pH level of yellowish rainwater was measured around 6.7. In compliance with the general expectation, major components in rainwater were of soil-origin such as Si, K, Ca, Ti and Fe. These soil-related components contributed to as much as 92% of total elemental composition in both soluble and insoluble fractions. By scanning a micro-beam, the residual particle cluster in individual raindrops was reconstructed in terms of an elemental map. This visualized elemental map in fact enabled us not only to estimate the chemical mixing state of raindrop residual particles but also to presume the wet scavenging of dust particles by rainfall.

Application of PIXE using Al funny filter for cluster analysis of Byzantine amphorae from Beirut

Particle induced X-ray emission (PIXE) has been employed to analyze Byzantine amphorae found during an extensive campaign of excavations of the historical center of Beirut. Cluster analysis was applied to the PIXE results to verify the origin of 39 selected amphorae, based on their elemental composition. Archeologists have previously identified these amphorae to be Byzantine and have distinguished two different types. The cluster analysis of the studied samples revealed that they had the same origin and can be both attributed to the Beirut production. In this paper we demonstrate that the use of an appropriate pinhole filter, so-called “funny filter”, as X-ray absorber, can offer considerable analytical advantages for the determination of elemental composition of thick target samples such as ancient ceramic materials. In fact, major, minor and trace elements can be obtained simultaneously in one run, instead of the two-run protocol employed in our previous work [M. Roumié et al., Nucl. Instr. and Meth. B 215 (2004) 196]. This can significantly reduce the acquisition time as well as the spectra treatment, especially when a large number of samples are to be studied.

Application of PIXE and XRD to the Characterization of Clays

The use of particle induced X-ray emission (PIXE) and X-ray diffraction as complementary techniques for the characterization of mineral samples (clays) is presented. The fundamentals of PIXE experiments, the method for performing quantitative analysis, and the actual results are also discussed.

Geological and mineralogical applications of PIXE: A review

We present a critical review of applications of particle induced X-ray emission (PIXE) analysis in geology and mineralogy. Applications are presented under the headings of conventional (macro-) beams and microbeams, further subdivided into consideration of bulk and preconcentrated samples. Inherent difficulties in bulk PIXE analysis of minerals are discussed, leading to the conclusion that preconcentration is essential for accurate PIXE analysis of trace elements. Preconcentration methods for the analysis of rare-earth and platinum group elements are highlighted. We examine factors in the recent successes of proton microprobe (PMP) laboratories in the geosciences. The PIXE microprobe can now be offered to geoscientists as a useful, routine and quantitative tool. With increasing availability of proton microprobes and awareness among geologists of the capabilities of PIXE, geoscience applications are likely to grow rapidly.

Application of particle-induced X-ray emission to research in biology and medicine

The analytical technique of particle-induced X-ray emission (PIXE) is described, and recent applications to problems in biomedical research are surveyed.