Beam Particle Induced X-ray Emission Research Articles

Physico-elemental analysis of roasted organic coffee beans from Ethiopia, Colombia, Honduras, and Mexico using X-ray micro-computed tomography and external beam particle induced X-ray emission

The physico-elemental profiles of commercially attained and roasted organic coffee beans from Ethiopia, Colombia, Honduras, and Mexico were compared using light microscopy, X-ray micro-computed tomography, and external beam particle induced X-ray emission. External beam PIXE analysis detected P, S, Cl, K, Ca, Ti, Mn, Fe, Cu, Zn, Br, Rb, and Sr in samples. Linear discriminant analysis showed that there was no strong association between elemental data and production region, whilst a heatmap combined with hierarchical clustering showed that soil-plant physico-chemical properties may influence regional elemental signatures. Physical trait data showed that Mexican coffee beans weighed significantly more than beans from other regions, whilst Honduras beans had the highest width. X-ray micro-computed tomography qualitative data showed heterogeneous microstructural features within and between beans representing different regions. In conclusion, such multi-dimensional analysis may present a promising tool in assessing the nutritional content and qualitative characteristics of food products such as coffee.

Investigations of minor elements in early aluminium artefacts

Study of the minor and trace element contents in the composition of early aluminium is interesting from a cultural history perspective because it can provide information on the evolution of aluminium smelting practice. A range of aluminium artefacts from the Swiss National Museum and the Lausanne Historical Museum, Switzerland, have been characterised with regard to their minor and trace element composition. This was performed using external beam Particle Induced X-ray Emission (PIXE) with 1 MeV protons and a portable X-ray fluorescence system. The concentration of Mn and Pb was significantly higher for artefacts produced by the amalgam process which confirms studies reported by others.

Croatian Appoxiomenos alloy composition and lead provenance study

An ancient bronze statue of an athlete with a strigil (known as Apoxiomenos) – was raised from the north Adriatic Sea in 1999. In order to help to determine its place and date of manufacture various scientific techniques were used. 14C dating performed by the Accelerator Mass Spectrometry (AMS) on the organic material found inside the statue gave calibrated dates between 100 B.C. and 250 A.D. Non-destructive analysis performed by portable X-Ray Fluorescence (XRF) system and external beam Particle Induced X-Ray Emission (PIXE) spectroscopy could not provide representative results for metal alloy composition due to the electrochemical deterioration of the surface of bronze in seawater. This was observed by the analysis of alloy cross-sections performed by the proton microprobe. The analysis showed much higher lead concentrations on the surface of the bronze than inside, confirming that realistic alloy composition can be only performed on samples taken from at least 0.6 mm below the surface. Subsequent micro-PIXE analysis on metal cross-section showed inhomogeneous lead concentrations between 1 and 12%. Lead isotope analysis for provenance investigation has been done on 15 samples using Multi Collector Inductively Coupled Plasma Mass Spectrometry (MC-ICP-MS). Analysis showed that lead isotope composition is consistent with some of the lead ores originating either from the Eastern Alps or from Sardinia. Altogether, the results lead to the conclusion that the statue is not of a Greek origin, but most probable it is a Roman copy of the Greek original.

PIXE and ionoluminescence for Mesoamerican jadeite characterization

AbstractGreenstones were highly appreciated in pre‐Hispanic Mesoamerica. Most of the finest green artifacts were worked in jadeite and other minerals such as serpentine and nephrite. Jadeite, the most precious stone in ancient Mesoamerica, was widely used and traded since the Preclassic Horizon (1500 B.C.). The main beds are located in the Maya region, in the Motagua area of Guatemala. In this work, three pieces of a necklace of greenstones from an offering (corresponding around 155 A.D.) discovered in an extensive excavation carried out in the palatial structure of Xalla, at Teotihuacan site, in the central highlands of Mexico, were studied using external beam particle induced x‐ray emission (PIXE). The necklace is composed by 11 round pieces of green colors ranging from light to dark green. The aim of this study is to determine the elemental composition of the greenstones and to establish the sourcing, trade and relationship between these regions. Thus, several jadeite samples from Manzanal sources of Motagua were analyzed as well. The elemental composition comparison between the archaeological items and the known jadeite samples indicates that only one archaeological piece is related to the Manzanal sample source. Green luminescence of high intensity was observed for the archaeological pieces but only in one case the luminescence was blue–violet. When comparing with green stone mineral samples, only jadeite presented luminescence. The spectra, corresponding mainly to Mn2+, Ce3+ and Al3+ emissions, were collected under proton induced luminescence in vacuum on the jadeite samples. No correlation was observed among light emission color and jadeite sources. Copyright © 2008 John Wiley & Sons, Ltd.

Rapid chemical state analysis by a highly sensitive high-resolution PIXE system

We have developed a crystal spectrometer system for rapid chemical state analysis by external beam particle induced X-ray emission. The system consists of a flat single crystal and a five-stacked position-sensitive proportional counter assembly. Chemical state analysis in atmospheric air within several seconds to several minutes is possible. A mechanism for time-resolved measurements is installed in the system. Performance of the system is demonstrated by measuring the time-dependence of chemical shifts of sulfur K α 1,2 line from marine sediment and aerosol samples.

Elemental Analysis of Artefacts in Air

Quantitative analyses of elemental content in historical and cultural artefacts using ion beam analysis (lBA) have been widely used, however, many artefacts are too large or sensitive to be placed in a vacuum which is required by most non-destructive physical analytical procedures. Ion beams can be safely brought from vacuum into air or other atmospheres (eg. helium) to strike the sample. Such a technique allows non-destructive analysis with the capability of measuring all elements heavier than aluminium, with sensitivities down to parts per million. During 1996, the Department of Applied Physics at Royal Melbourne Institute of Technology in consultation with the Conservation Department of the Museum of Victoria developed an external beam particle induced X-ray emission (PIXE) analysis system. This system allows a beam of ions to fall on an artefact in air generating characteristic X-rays in a similar way to energy dispersive X-ray spectrometry on a scanning electron microscope (SEM). The X-rays are detected allowing quantitative assay of the elements heavier than aluminium in artefacts. Sensitivity of the technique is dependent on the elemental composition of the artefact, but it can be as low as 10 ppm. As the beam is extracted into air, very large objects can be analysed. Other atmospheres can also be used including helium, nitrogen and vacuum. The technique is non-destructive with the vast majority of samples. Studies so far have concentrated on the origin of paint pigments and glasses from an ancient temple in the Egyptian Western Desert, historically important processes for protecting steel from corrosion, and the content of ancient bullets.

Analyses of Sulfur Aerosol Size Distributions for a Forty-Day Period in Summer 1992 at Meadview, Arizona

A DRUM (Davis Rotating-drum Universal-size-cut Monitoring) impactor was employed at Meadview, AZ, from July 12 to September 2, 1992, during the Project MOHAVE (Measurement of Haze and Visual Effects) summer intensive monitoring period. The DRUM impactor collects aerosol from 0.07- to 15-μm diameter in eight size ranges on the outside curved surface of eight drums rotating one revolution per month. Focused beam PIXE (Particle Induced X-ray Emission) analysis of the aerosol deposits results in a time history of size-resolved elemental composition with 6-hour resolution. Comparisons of the component composition of less than 2.5-μm diameter particles from the DRUM impactor with the composition of the PM2.5 from the collocated IMPROVE (Interagency Monitoring of Protected Visual Environments) filter sampler are used to assess the quality of DRUM data. Comparisons are also made of the sulfur concentrations in three size ranges below 2.5 μm as measured by the DRUM and MOUDI (Micro Orifice Uniform Deposit Impactor) samplers. From these analyses a 40-day period of DRUM sulfur data (155 6-hour time periods) is identified for subsequent use to generate and analyze sulfur size distributions. Techniques to display and summarize these sulfur size distribution histories are developed, including contoured plots of sulfur concentration by size and time, and cluster analysis. The results indicate that all periods can be well represented by several distinct size distributions. Relationships between these characteristic distributions and coincident meteorological, air quality, and optical parameters are determined and the consequences of these relationships discussed.

Quantitative trace element analysis of human nails with external beam PIXE

External beam PIXE (Particle Induced X-ray Emission) analysis with a proton beam of 2.4 MeV was used to study trace element concentrations in human nails. The suitability of PIXE analysis regarding nail samples without any pretreatment besides washing was investigated. The main emphasis has been on the ability to obtain absolute concentration values and a new accurate method for nail sample standardization has been developed. Concentration values for the elements Ca, Cr, Mn, Fe, Ni, Cu, Zn, Se, Br, and Pb were determined from human nail samples. A comparison was made with nail samples taken from different fingers and toes to monitor intraindividual variation, and nails of different healthy individuals to get a view of the interindividual differences. The concentrations were also measured in relation to time in order to observe any possible short-term changes. The results are compared with the previous studies reported in the literature. The nail analysis is also compared to hair analysis in terms of detection limits, number of elements determinable, and standardization of the results.