X-ray fluorescence microtomography

Another example of the utility of mapping the spatial distribution of trace elements and their association with other elements or phases comes from a recent X-ray fluorescence microtomography study of the spatial distribution of Pb, Fe, Mn, Zn, and As on and within the roots of Phalaris arundinacea, a common aquatic plant from a mine waste impacted wetland in the Coeur d Alene Basin of northern Idaho (Hansel et al. 

Figure 9. Metal distribution on and within a cross-section of grass root (Phalaris arundinacea) as determined by x-ray fluorescence microtomography at the Advanced Photon Source (GSECARS, beam line 13- - ). The lightest colored areas in the tomographs represent the highest concentrations of each element. The scale bar in the upper left panel is 300 pm, and is representative of the scale in the other panels, (after Hansel et al. 2001)...

Figure 27. Metal distributions on the root surface of Phalaris arundimcea obtained by X-ray fluorescence microtomography. Pb and Fe are concentrated in the surficial rind on the epidermis and have similar distribution patterns. These images have been converted to negative-contrast grayscale from their original forms published by Hansel et al. (2001). Mn, Zn, and Ca are correlated and exist as discrete aggregates.

Lawrence Livermore National Laboratory Report UCRL-50174 sec II revision I Menez B, Simionovici A, PhiUppot P, Bohic S, Gibert F, Chukalina M (2001) X-ray fluorescence microtomography of an individual fluid inclusion using a third generation synchrotron light source. Nucl Instrum Methods Phys Res 181 749-754... 

Sutton SR, Rivers ML (1999) Hard X-ray synchrotron microprobe techniques and applications. In Synchrotron Methods in Clay Science. CMS Workshop Lectures Vol. 9. Schulze DG, Stucki JW, Bertsch PM. (eds). The Clay Mineral Society, Boulder CO, p 146-163 Sutton SR, Flynn G, Rivers M, Newville M, Eng P (2000) X-ray fluorescence microtomography of individual interplanetary dust particles. Lunar Planet Sci XXXI 1857 Sutton SR, Rivers ML, Bajt S, Jones KW, Smith JV (1994) Synchrotron X-ray-fluorescence microprobe-a microanalytical instrument for trace element studies in geochemistry, cosmochemistry, and the soil and environmental sciences. Nucl Instrum Methods Phys Res A 347 412-416 Suzuki Y, Awaji M, Kohmura Y, Takeuchi A, Takano H, Kamijo N, Tamura S, Yasumoto M, Handa (2001) X-ray microbeam with sputtered-shced Fresnel zone plate at SPring-8 undulator beamline. Nucl Instrum Methods Phys Res A 467-468 951-953... 

Figure 3 (A) Schematic drawing of an X-ray fluorescence microtomography set-up that (B) allows the collection of elemental distributions from a single horizontal slice of the sample. Further slices are obtained by translation.

Abstract This chapter deals with the analytical applications of synchrotron radiation sources for trace-level analysis of materials on microscopic and submicroscopic scales. Elemental analysis with X-ray fluorescence is described in detail. Two-dimensional (2D) and three-dimensional (3D) analyses are discussed in their quantitative aspects. Related methods of analysis based on absorption edge phenomena such as X-ray absorption spectrometry (XAS) and near-edge scanning spectrometry (XANES) yielding molecular information, computerized X-ray fluorescence microtomography (XFCT) based on the penetrative character of X-rays, and microscopic X-ray diffraction (XRD) providing structural data on the sample are also briefly discussed. The methodological treatment is illustrated with a number of applications. 

He then spent three years as a postdoctoral member of the technical staff at AT T Bell Laboratories, Murray Hill NJ, where he conducted research of the structure, kinetics, and phase transitions of surfaces and interfaces, using X-ray diffraction. He is currently as Senior Research Scientist in the James Franck Institute and Consortium for Advanced Radiation Sources (CARS) at the University of Chicago. He has been involved in synchrotron radiation research since 1986 and during the past seven years has been involved in the design, construction and operation of the GeoSoilEnviroCARS (GSE)CARS laboratory at the Advanced Photon Source. Here he has applied lower dimensional X-ray diffraction, X-ray absorption fine structure, X-ray fluorescence microprobe, microtomography and microcrystallography to study problems in earth and environmental science. 

Abbreviations AES, Auger emission spectrometry CRM, Certified reference material DL, Detection limit ED, Energy dispersive ESRF, European Synchrotron Radiation Facility EXAES, Extended X-ray absorption fine structure NEXAFS, Near edge X-ray absorption fine structure PCI, Phase contrast imaging RM, Reference material SR, Synchrotron radiation SRM, Standard reference material TXRF, Total reflection X-ray fluorescence XANES, X-ray absorption near edge structure XAS, X-ray absorption spectrometry XDM, X-ray diffraction microscopy XFCT, X-ray fluorescence computerized microtomography XPEEM, X-ray photoelectron microscopy XPS, X-ray photoelectron spectrometry XRD, X-ray diffraction XRF, X-ray fluorescence... 

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