X-ray microprobes

X-ray microprobe Diffusion coefficient Self-diffusion coefficient of a liquid Rotational correlation time... 

Janssens, K., Aerts, A., Yincze, L., et al. (1996). Corrosion phenomena in electron, proton and synchrotron X-ray microprobe analysis of Roman glass from Qumran, Jordan. Nuclear Instruments and Methods B 109-110 690-695. 

Heald, S.M., Cross, J.O., Brewe, D.L, Gordon, R.A. 2007. The PNC/XOR X-ray microprobe station at APS sector 20 Proceedings of the 14th National Conference on Synchrotron Radiation Research - SRI 2007. Nuclear Instruments and Methods in Physics Research Section A, 582, 215-217. 

Krantzberg G, Stokes PM. 1990. Metal concentrations and tissues distribution in larvae of chironomus with reference to x-ray microprobe analysis. Arch Environ Contain Toxicol 19 84-93. 

Clean flat glass and waste carpet fibers were used in this study. The chemical composition of the glass was analyzed using an X-ray microprobe analyzer and listed in Table 2 together with that of silica fume and rice husk ash for comparison. 

Ilinski P, Lai B, Cai Z, Yun W, Legnini D, Talarico T, Cholewa M, Webster LK, Deacon GB, Rainone S, Phillips DR, Stampfl APJ. The direct mapping of the uptake of platinum anhcancer agents in individual human ovarian adenocarcinoma cells using a hard x-ray microprobe. Cancer Res. 2003 63 1776-1779. 

Elements other than vanadium are accessible to the EXAS technique. Thus, abundant sulfur detected in tunicate blood cells has been identified as sulfate and sulfonate with EXAS (150). This result confirmed a similar finding carried out with chromatographic techniques (151). With this background, let us now consider the X-ray microprobe analyses of timicate blood cells. 

These results support the electron X-ray microprobe studies. The term vanadocyte as applied to a single cell appears to be a misnomer as vanadium is distributed in more than a single cell in at least five species of the genus Ascidia and one of dona. Although certainly a more accurate description of vanadium histochemistry, this finding leaves unanswered the question of how vanadium is accumulated in such a low oxidation state. 

A composition of the crystals was determined by X-ray microprobe analysis using a "Cameca - SXlOO" device. Equilibrium and lattice parameters of FeIn2S4 crystals were determined by X-ray diffraction (XRD) method. XRD patterns were recorded with a DRON-3M diffractometer using Cu radiation and a graphite monochromator. 

The results of X-ray microprobe analysis revealed that the concentration of elements in the grown crystals (Fe In S = 13.94 28.34 57.72 at.%) is in good agreement with composition in the precursor mixture... 

The chemical composition and structure throughout the lesions were evaluated using an SEM in conjunction with X-ray microprobe analysis (EMPA) and TOF SIMS. EMPA senses the chemistry of the sample to a depth of around 1 xm, while TOF SIMS is a surface technique that only identifies the surface atoms/ions. 

Iwai-Liao Y, Higashi Y, Guo L, Ogita Y, Nonaka T Fine structure study and energy dispersive spectroscopy (EDS) X-ray microprobe (EDX) analysis of organic elements in the human enamel. JTrace Microprob Tech 1997 15 673-682. 

Chemical analysis of a very small region in a large sample is called microanalysis. The diameter of the analyzed region is of the order of a micron or less. Such analysis can be done with an x-ray microprobe (x-ray microanalyzer) or with various forms of the electron microscope, if the latter is equipped with an x-ray spectrometer. 

For surface structure studies, perhaps the most popular technique has been LEED (373). Elastically diffracted electrons from a monoenergetic beam directed to a single-crystal surface reveal structural properties of the surface that may differ from those of the bulk. Some applications of LEED to electrocatalyst characterization were cited in Section IV (106,148,386). Other, less specific, but valuable surface examination techniques, such as scanning electron microscopy (SEM) and X-ray microprobe analysis, have not been used in electrocatalytic studies. They could provide information on surface changes caused by reaction, some of which may lead to catalyst deactivation (256,257). Since these techniques use an electron beam, they can be coupled with previously discussed methods (e.g. AES or XPS) to obtain a qualitative mapping of the structure and composition of a catalytic surface. 

Fig. 4-6. X-ray microprobe analysis of SO4 distribution along equatorial axis of single resin bead at different fractional conversion, F (from Petruzzelli aod Boghetich, 1983).

Gel-type, microporous, resins must swell to expose their catalytically active sites, whereas macroreticular resins have a permanent pore structure (inside these pores, catalytically active sites reside). Pores of the macroreticular resins can be described acceptably in terms of the conventional cylindrical pore model (pore diameter and volume). Pore structure, size, pore volume, and so on have been studied intensively in recent years. Examples of analytical techniques include X-ray microprobe analysis, ESR spectroscopy, NMR, and inverse steric exclusion chromatography (ISEC) the latter yields the best quantitative assessment of the nanomorphology of swollen resins. 

In one example [14], millimeter-sized particles of polystyrene were chlorometh-ylated, then functionalized with phosphino groups and, eventually, the phosphi-nated material was reacted with rhodium] I) complexes. By means of X-ray microprobe analysis (XRMA), the penetration of the reactants towards the core of the particles was estimated from the distribution of chlorine, phosphorus and rhodium atoms in the material as determined by XRMA after each step. The higher the cross-linking degree, the more difficult is the penetration of the reacting species. Table 11.1 below lists the techniques studied for determination of pore structure. 

Chou et al. [45, 46] made a detailed study of pure methane hydrates in a HD AC by visual, Raman, and X-ray microprobe techniques. Their results revealed two previously unknown high-pressure structures, sll and sH. At 250 MPa sll has a cubic unit cell of a = 17.158 A. At 600 MPa sH has a hexagonal unit cell of a = 11.980 A and c = 9.992 A. The compositions of these two phases are still not known. They conclude that within deep hydrate bearing sediments underlying continental margins, and in the presence of other gases in the structure, the sll phase is likely to dominate over the si phase. 

Direct evidence for the formation of authigenic metal sulfide comes from x-ray microprobe and light-microscope examination of the salt-marsh sediments. In the presence of sulfur, iron monosulfides react to form pyrite, FeS2, which is known to occur as distinctive, characteristic aggregates of octahedral microcrystals of FeSj (framboids Berner, 1970 Sweeney and Kaplan, 1973). In the Farm River samples, framboidal FeSj was found to be common within at least the upper 14 cm of core examined, either as discrete framboids of 10- im diam. (Fig. 7) or as ordered clusters of framboids. Inspection of polished thin sections reveals a frequent association with the organic matrix, which appears to act as a template for their formation (see Fig. 8). 

Bajt S, Clark SB, Sutton SR, Rivers ML, Smith JV (1993) Synchrotron X-ray microprobe determination of chromate content using X-ray absorption near-edge structure. Anal Chem 65 1800-1804 Balistrieri L, Brewer PG, Murray JW (1981) Scavenging residence times of trace metals and surface chemistry of sinking particles in the deep ocean. Deep-Sea Res 28A 101-121 Banfield JF, Barker WW, Welch SA, Taunton A (1999) Biological impact on mineral dissolution application of the lichen model to understanding mineral weathering in the rhizosphere. Proc Nat Acad Sci USA 96 3404-3411... 

Bertsch PM, Hunter DB (2001) Applications of synchrotron-based X-ray microprobes. Chem Rev 101 1809-1842... 

Thompson AC, Underwood JH, Wu Y, Giauque RD, Jones KW, Rivers ML (1988) Elemental measurements with an X-ray microprobe of biological and geological samples with femtogram sensitivity. Nucl Instrum Meth Phys Res A 266 318-323 Thompson HA, Brown GE Jr, Parks GA (1995) Low and ambient temperature XAFS study of U(VI) in solids and aqueous solutions. Physica 208 209 167-168 Thompson HA, Brown GE Jr, Parks GA (1997) XAFS spectroscopic study of uranyl coordination in solids and aqueous solution. Am Mineral 82 483-496... 

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