Spectroscopy X-ray absorption near-edge structure

XANES X-ray absorption near edge structure spectroscopy... 

A reevaluation of molecular structure of humic substances based on data obtained primarily from nuclear magnetic resonance spectroscopy, X-ray absorption near-edge structure spectroscopy, electrospray ionization-mass spectrometry, and pyrolysis studies was presented by Sutton and Sposito (2005). The authors consider that humic substances are collections of diverse, relatively low molecular mass components forming dynamic associations stabilized by hydrophobic interactions and hydrogen bonds. These associations are capable of organizing into micellar structures in suitable aqueous environments. Humic components display contrasting molecular motional behavior and may be spatially segregated on a scale of nanometers. Within this new structural context, these components comprise any molecules... 

Techniques of microscopic XRF ( j,-XRF) developed in the last 20 years provide 2D images and elemental maps of each element present in the target material. Portable/in situ p-XRF, j,-XRF spectrometers synchrotron-based ( -SRXRF) and micro-x-ray absorption spectroscopy/micro-x-ray absorption near-edge structure spectroscopy (XAS/ J,-XANES) have improved the mineralogical characterization, as well as the elemental and chemical imaging of samples at the submicrometer scale [61]. 

X-ray fine-structure spectroscopy has been used to determine the Cr(VI) Cr(III) ratio in soils [91]. The Cr(VI) Cr(III) ratio in extracts of soils has been determined using X-ray absorption near-edge structure spectroscopy [92]. 

Brandes, J. A., Lee, C., Wakeham, S., Peterson, M., Jacobsen, C., Wirick,S., and Cody, G. (2004). Examining marine particulate organic matter at sub-micron scales using scanning transmission X-ray microscopy and carbon X-ray absorption near edge structure spectroscopy. Marine Chem. 92,107-121. 

Sarret, G., Connan, J., Kasrai, M., Bancroft, G. M., Charrie-Duhaut, A., Lemoine, S., Adam, P., Albrecht, P., and Eybert-Berard, L. (1999). Chemical forms of sulfur in geological and archaeological asphaltenes from Middle East, France, and Spain determined by sulfur K- and L-edge X-ray absorption near-edge structure spectroscopy. Geochim. Cosmochim. Acta 63, 3767-3779. 

Vairavamurthy M. A., Maletic D., Wang S., Manowitz B., Eglinton T. I., Lyons T., and Anonymous (1997) Characterization of sulfur-containing functional groups in sedimentary humic substances by X-ray absorption near-edge structure spectroscopy. Energy and Fuels 11, 546-553. 

Solid-phase speciation has been measured both by wet chemical extraction and, for arsenic, by instrumental methods principally X-ray absorption near edge structure spectroscopy (XANES) (Brown et al., 1999). La Force et al. (2000) used XANES and selective extractions to determine the likely speciation of arsenic in a wetland affected by mine wastes. They identified seasonal effects with As(El) and As(V) thought to be associated with carbonates in the summer, iron oxides in the autumn and winter, and silicates in the spring. Extended X-ray absorption fine stmcture spectroscopy (EXAES) has been used to determine the oxidation state of arsenic in arsenic-rich Californian mine wastes (Eoster et al., 1998b). Typical concentrations of arsenic in sods and sediments (arsenic <20 mg kg ) are often too low for EXAFS measurements, but as more powerful photon beams become available, the use of such techniques should increase. 

Urquhart SG, Ade HW (2002) Trends in the carbonyl core (C Is, Is) to n transition in the near edge X-ray absorption fine structure spectra of organic molecules. JPhys Chem 106 8531-8538 Vairavamurthy A, Manowitz B, Zhou W, Jeon Y (1994) Determination of hydrogen sulfide oxidation products by sulfur -edge X-ray absorption near edge structure spectroscopy. In Environmental Geochemistry of Sulfide Oxidation. Alpers CN, Blowes DW (eds) Am Chem Soc Symp Series, Vol 550, Am Chem Soc, Washington, DC, p 412-430... 

The formation and dissociation of S-S bonds in poly(tricyanuric acid), which is proposed as electrode material for lithium batteries, has been studied [590,591]. The reversibility of the process essential for the use of this material in a secondary battery could be established. Further studies of battery materials have been reported [592, 593]. X-ray absorption near edge structure spectroscopy has been successfully employed in studies of inhibiting species in passive films and the adjacent electrolyte solutions. 

Infrared spectroscopy, NMR spectroscopy, X-ray methods such as X-ray absorption near-edge structure spectroscopy and ESR spectroscopy have been used primarily to probe the detailed chemistry of heteroatom speciation, polar functional group determination, and hydrogen and carbon types in asphaltenes. The consensus seems to indicate that most asphaltene molecules have one to three heteroatoms (S, N, and O) per molecule. Sulfur exists predominantly as thio-phenic heterocycles (typically 65—85%) with the remainder as sulfidic groups (46,47). Thiophenic moieties are not... 

We also have succeeded in characterizing the SEI on the cathode formed in 1 M LiPF PC + DMC (50 50 vol%) + 5 wt% ES by an x-ray absorption near edge structure spectroscopy (XANES) for the first time. The compounds deposited on the cathode were different from those on the anode, and Li SO was detected as well as other organic snlfur compounds, as shown in Fig. 4.13. It is reasonable that ES is oxidized to SO species on the cathode, while Li SOj exists on the anode. In-situ electrochanical impedance spectra showed that the SEI formed by ES showed higher film resistance than that by VC, as in the case of the anode. ... 

Methods of growing importance for speciation and complexation studies of actinides are the synchrotron-based X-ray absorption near-edge structure spectroscopy (XANES) and the extended X-ray absorption fine structure spectroscopy (EXAFS). 

Analysis of a metallodrug in a biological tissue is a challenging task in analytical chemistry, primarily because the traditional methods used are usually indirect and semi-quantitative to a large extent, and are unable to visualize the metal ions in vivo. Advanced nuclear analytical techniques, such as X-ray fluorescence, neutron activation analysis. X-ray emission. X-ray absorption near-edge structure spectroscopy, nuclear magnetic resonance, and isotope tracing/dilution techniques offer some means by which elemental distribution, oxidation states, and species structural information can be studied. ... 

In this work, we investigate the formation of hexagonal boron nitride (h-BN) fiom the tribochemical reaction between a borated additive and a nitrogenous compound. We developed a multitechnique approach including X-Ray Photoelectron Spectroscopy (XPS), X-ray Absorption Near Edge Structure Spectroscopy (XANES), Electron Energy Loss Spectroscopy (EELS) and high resolution TEM (HRTEM). 

Frank, P., Hedman, B., Carlson, R.M.K., Tyson, T.A., Roe, A.L, and Hodgson, K.O. (1987) A large reservoir of sulfate and sulfonate resides within plasma cells from Ascidia ceratodes, revealed by X-ray absorption near-edge structure spectroscopy. Biochemistry, 26, 4975-4979. 

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