Proton-Induced Ten-Ray Emission

Radioactive decay and Our Well-Being

Michael F. L'Annunziata , in Radioactivity (2d Edition), 2016

i.half dozen.five.b Proton-Induced Ten-Ray Emission (PIXE)

PIXE is a nondestructive analytical technique used to determine the elemental content of a substance from the X-ray emissions caused past the irradiation of the substance with protons. The technique involves the irradiation of a substance with protons accelerated at an energy of ∼3   MeV. Accelerated protons collide with inner orbital electrons (K or L orbital) of the elements in the sample nether assay, resulting in a pour of electrons falling from outer higher-energy orbitals to inner orbitals with a concomitant emission of X-radiations at energy lines characteristic of each element. A suitable detector of X-rays emitted by the sample, such as south silicon drift detector, is used to measure the intensities of the 10-rays emitted at different free energy lines, from which the elements in the substance nether analysis can be identified and quantified (Verplancke et al., 2012). The elements are identified according to the X-ray energy lines that are feature of each element; and the X-ray intensities at specific energies are used to quantify each chemical element in the sample under analysis. Pure chemical element standards serve every bit reference fabric to calibrate the X-ray detector response to X-rays emitted by the sample at various energy lines. A typical spectrum resulting from the PIXE analysis of paint used by Antonello de Messina, 1 of the great Italian masters of the 15th century, in the famous painting "Ritratto Trivulzio" is illustrated in Fig. 1.44.

Figure 1.44. The "Ritratto Trivulzio" by Antonello de Messina at the scanning microbeam line at the Laboratorio di tecniche nucleari per i Beni Culturali of the Instituto Nazionale di Fisica Nucleare, Florence, Italy. The overlapping graph illustrates 10-ray summit intensities for the elements Ca, Fe, and Cu in a spot of the dark headcloth in the painting. The pigment used for the headcloth was identified equally a Cu-based pigment, such as the blue paint azurite.

 Figures from Grassi, Northward., 2009. Differential and scanning-mode external PIXE for the assay of the painting "Ritratto Trivulzio" by Antonello da Messina. Nucl. Instrum. Methods Phys. Res. Sect. B 267, 825–831, reprinted with permission from Elsevier © 2009.

PIXE is an fantabulous method for elemental analysis when a nondestructive method is required for the measurement of elements of atomic number greater than eleven (Z  >   11). The assay of elements of depression diminutive number (Z  <   17), including Li, B. F, Na, Mg, Al, and Si, can be carried out with proton-induced gamma-ray analysis (PIGE) resulting from nuclear reaction between accelerated protons and the nuclei of the light elements. The light elements have a lower coulomb barrier than the heavier elements, and thus protons accelerated at energies of simply two.0–iii.5   MeV volition interact with the nuclei of the light elements, with the concomitant emission of gamma radiation. Because proton energies used in PIGE are like to those used in PIXE, both methods of assay may exist used simultaneously. The acronym PIXE may besides refer to particle-induced 10-ray emission, as other particles, such as the accelerated electrons, may be used in lieu of accelerated protons; nonetheless, accelerated electrons produce considerable bremsstrahlung radiation, which tin can interfere with the measurement of X-radiations emitted by the sample nether analysis. PIXE is also known every bit a grade of ion axle assay, because a beam of charged particles is accelerated to collide with a sample to clarify its elemental composition from the resulting radiations emissions.

PIXE is useful in analyzing materials that should not be destroyed, such equally analysis required in the measurement and characterization of prehistoric pigments and ancient artifacts, and the characterization of paints used past the masters of centuries past. Excellent examples of PIXE analysis in studies of cultural heritage and reviews on its applications are bachelor from Grassi (2009), Sokaras et al. (2011), Jeynes et al. (2012), Kakuee et al. (2012), Beck (2014), Rizzutto et al. (2014), and Zucchiatti and Redondo-Cubero (2014).

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A Synchrotron Ten-ray diffraction study of Egyptian cosmetics

P. Martinetto , ... Ph. Walter , in Radiation in Art and Archeometry, 2000

5 Decision

The assay of cosmetics as used in Ancient Egypt reveals the groovy variety of compositions using pb compounds and an advanced know-how in chemic synthesis. This shows that 4000 years ago, people already wanted more impact from their use of cosmetics than simply highlighting of the eyes. This piece of work shows the benefits of combining optical and electronic microscopy methods, X-ray fluorescence measurements and ion beam assay (Proton-Induced Ten-ray Emission, Rutherford Backscattering Spectrometry, Nuclear Resonance Analysis) with X-ray diffraction in view of identifying and weighing the crystalline phases in archaeological or artistic objects. The use of X-ray synchrotron radiation enables one to examine small-scale volumes of rare and precious, highly X-ray arresting powders, without whatever amending prior to the analysis. The high resolution and loftier betoken-to-groundwork ratio make it possible to determine the composition of complex mixtures, particularly when the specimen is composed of a large number of phases or when some ingredients are present in extremely modest proportions (< 1%). The assay of the Bragg line profiles could also provide some insight into the micro-structure of some minerals (size and distortions of the grains), in relation with the preparation of the brand-up (synthesis, grinding, sieving).

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Radiation Methods of Matter Composition Analysis

Ilya Obodovskiy , in Radiation, 2019

20.ane.ii Particle-Induced 10-Ray Emission

The start PIXE as a powerful analytical method was demonstrated in 1970 by S.A.Eastward. Johansson. For registering 10-ray quanta, Johansson used the Si (Li) detector that had just become available. Subsequently this, PIXE became a widely used method for analyzing the elemental composition of a substance.

Battery by charged particles tin be performed by either of the sources, generally alpha sources, or of accelerators. In this case, the set up of possible particles is significantly expanded. The protons are most oft used and then the acronym PIXE stands for proton-induced Ten-ray emission. The PIXE analyzer circuit is shown in Fig. 20.1.

Effigy 20.1. The essential parts of the particle-induced X-ray emission setup.

 Fig. from Instrumentation for PIXE and RBS. IAEA-TECDOC-1190, IAEA, 2000. http://world wide web-pub.iaea.org/MTCD/publications/PDF/te_1190_prn.pdf with permission of IAEA.

Solid samples can be analyzed every bit they are presented for analysis, every bit powder and fibroid materials, if necessary, are subjected to additional crushing, and from them tablets are compressed, which are then analyzed. Liquids tin also be analyzed directly in special containers with a thin lid every bit a window for radiation. And only potent acids or alkalis may require dilution. Aerosols adsorbed on the filter tin can besides be directly analyzed, as some measures are taken to forbid boosted contamination of the filters.

The energy of the feature quanta is adamant either by means of instruments having a good energy resolution or past dividing the X-ray quanta along the wavelengths by a crystal diffraction method.

To determine the exact quantitative content of the element, it is necessary to ensure the calibration of the device. Ane of the possible ways of calibration is the use of standard samples, which elemental composition is precisely known. By processing the results, the particle path in the analyzed sample must be considered, whether they fly through it or stop in the thickness of the sample. As to developers of equipment for analysis, they take measures to equalize the sensitivity to elements with different atomic weights.

It is believed that the PIXE method presents more authentic results than XRF. Thus, the beam of particles tin be better focused and the assay of microparticles or microdistribution of the elements in the sample with a spatial resolution of the social club of 10   μm tin can exist provided.

The annual International Conferences PIXE was devoted to the application of the PIXE method, and the materials were published. The final was the 15th International Conference on Particle-Induced X-ray Emission (PIXE 2017) [4]. One of the previous conferences has several sections, which shows the range of possible areas of the method applications: PIXE in studies of the environment, atmosphere, archaeology, fine art, substance characteristics, biological science and medicine, agriculture, and food industry.

Here are 2 examples of the application of the PIXE method for analysis.

The concentration of cesium in rice grains grown on the territories around the Fukushima nuclear power plant after the accident was examined [5]. With a resolution of i   ×   1   μm2, the studies made information technology possible to obtain a picture of spatial distribution of cesium in a separate rice grain. Studies have shown that radioactive cesium is concentrated on the grain surface and its amount decreases by nigh 40% by polishing the grain.

In the study [6], the elemental composition of green and roasted coffee grains, besides every bit ground java, was investigated. The main components of coffee beans are carbon 84%, oxygen 11.5%, and nitrogen 4.5%. Besides, there are many other elements shown in the spectrum of Fig. 20.2. The authors plant a divergence in chlorine content in the fried grains and in freshly ground coffee and associated with this the best taste of freshly ground java. Green and fried grains accept the same elemental composition, which means that during the roasting process the elements are not removed.

Figure 20.2. Typical particle-induced X-ray emission spectrum of roasted coffee beans ground correct before the experiment. The Ten-ray yield was normalized by the total charge accumulating during experiment. The energy of the photon beam was two   MeV with an boilerplate current of nigh 5   nA. The irradiation time was 400   s.

 Figure from R. Debastiani, C.E.I. dos Santos, Thousand.L. Yoneama, L. Amaral, J.F. Dias, Ion axle analysis of ground java and roasted java beans, Nucl. Instrum. Methods B 318 Part A (2014) 202–206 with permission.

In 2010, the XRF method was used for the noncontact determination of the in situ characteristics of 7 paintings (including the Mona Lisa) straight in the Louvre Museum. The results, which were published in July 2010, helped to identify and study the techniques used by the masters of the past, due east.g., the famous "sfumato" style used past Leonardo da Vinci.

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Thin and thick target PIXE analyses to assess the mechanism of Cu2+ removal by Egeria densa

F.R. Espinoza-Quiñones A.N. Módenes Grand.H.F. Santos C.Due east. Borba Thou.A. Rizzutto Mauro A.S.S. Ravagnani , in Practical Radiation and Isotopes, 2013

4 Determination

The PIXE technique is an excellent belittling tool for measurements of element concentrations in liquid and solid samples, its analytical adequacy being corroborated mainly in solid samples without a previous pretreatment. With the computer programme Clara it was possible to calculate the correction cistron associated with matrix limerick in solid samples, allowing determinations of the element concentrations with high reliability and reproducibility of data. From the set of major elements identified and quantified, in equivalents, in the liquid and solid phases copper removal experiments using E. densa biosorbent, Na+, K+, and Ca2+ cations leap to the biosorbent surface are primarily exchanged for Cu2+ at pH 5.

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TOF-SIMS in cosmochemistry

Thomas Stephan , in Planetary and Space Science, 2001

Surface analysis with TOF-SIMS followed to study contamination furnishings (see higher up). Subsequently, the particles were investigated with PIXE (proton induced X-ray emission) analysis including STIM (scanning transmission ion microprobe). PIXE allows trace element studies with high sensitivity down to ppm levels for elements with atomic numbers >11 (Traxel et al., 1995; Bohsung et al., 1995). STIM yields particle densities and masses (Maetz et al., 1994; Arndt et al., 1996c, 1997). This first PIXE investigation was done at limited proton current and dose to avoid destruction of hydrous minerals (Maetz et al., 1996). The information depth in PIXE is of the order of 30 μm , the typical dimension of the dust particles. The information in SEM-EDS comes from the upper ane– ii μm , and TOF-SIMS just investigates the surface. Consequently, even for elements that are detectable with all 3 analytical techniques, the results are non straightforward to compare (Stephan et al., 1995b).

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