X-ray adsorption

XANES X-ray adsorption nearedge spectroscopy [178a] Same as NEXAFS Same as NEXAFS... 

Schertel A, Hahner G, Grunze M and Well C 1996 Near edge x-ray adsorption fine structure investigation of the... 

Elder, R.C., Tepperman, K.G., Eidsness, M.K., Heeg, M.J., Shaw, C.F. Ill and Schaeffer, N. A. (1983) Gold-based antiarthritic drugs and metabolites. Extended x-ray adsorption fine structure (EXAFS) spectroscopy and x-ray absorption near edge spectroscopy (XANES). ACS Symposium Series, 209, 385-400. 

It has been observed that cobalt may undergo large-scale reconstruction under a synthesis gas environment.27 Reconstruction is a thermodynamically driven process that results in the stabilization of less reactive surfaces. Recent molecular modeling calculations have shown that atomic carbon can induce the clock reconstruction of an fee cobalt (100) surface.28 It has also been postulated and shown with in situ x-ray adsorption spectroscopy (XAS) on cobalt supported on carbon nanofibers that small particles (<6 nm) undergo a reconstruction during FTS that can result in decreased activity.29... 

V has been elucidated by x-ray adsorption spectroscopy [5]. Gold has an fee lattice, and the Au(lll) surface forms a triangular lattice with a lattice constant of 2.89 A. Copper atoms are smaller than gold atoms, and they adsorb in the threefold hollow sites (see Fig. 4.12), forming a triangular lattice commensurate with that of the substrate ... 

Many of the characterization techniques described in this chapter require ambient or vacuum conditions, which may or may not be translatable to operational conditions. In situ or in opemndo characterization avoids such issues and can provide insight and information under more realistic conditions. Such approaches are becoming more common in X-ray adsorption spectroscopy (XAS) methods ofXANES and EXAFS, in NMR and in transmission electron microscopy where environmental instruments and cells are becoming common. In situ MAS NMR has been used to characterize reaction intermediates, organic deposits, surface complexes and the nature of transition state and reaction pathways. The formation of alkoxy species on zeolites upon adsorption of olefins or alcohols have been observed by C in situ and ex situ NMR [253]. Sensitivity enhancement techniques play an important role in the progress of this area. In operando infrared and RAMAN is becoming more widely used. In situ RAMAN spectroscopy has been used to online monitor synthesis of zeolites in pressurized reactors [254]. Such techniques will become commonplace. 

Soil samples were collected systematically down a 2 m deep colluvial soil profile located over Au mineralisation at the Bounty Gold Deposit (Yilgarn Craton, Western Australia), prior to mining. Bulk samples were analysed by ICP-AES, ICP-MS and XRD and further sub-sampled and analysed to ensure that they contained detectable Au prior to detailed analysis by LA-ICP-MS, SXRF and x-ray adsorption near edge spectrometry (XANES). 

X-ray absorption spectroscopy (XAS) Methods that use X-rays to investigate the physical and chemical properties of materials on an atomic scale. XAS includes X-ray adsorption fine structure (XAFS) spectroscopy and its X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectra. 

Salama, T. M., Hattori,H., Kita,H., Ebitani, K., and Tanaka, T., X-ray adsorption spectroscopic and electron paramagnetic resonance studies on the strong metal-support interaction of platinum supported on titania dispersed on silica, J. Chem. Soc. Faraday Trans. 89(12), 2067 (1993). 

HREELS108 and surface extended X-ray adsorption fine structure (SEXAFS)109 measurements reveal that Si—O—Si complexes exist in the early stage of oxidation. Based on... 

NEXAFS Near-Edge X-ray Adsorption Fine Structure... 

XANES X-ray Adsorption Near-Edge Structure Another name for NEXAFS. 

A few structures have been solved by x-ray adsorption near-edge fine structure (XANES), including oxygen on Ni(100)./16/ This technique is also known as near-edge x-ray adsorption fine structure (NEXAFS). 

A number of different experimental methods are available to observe fine structure. In extended x-ray adsorption fine structure (EXAFS) experiments x-ray photons excite core levels and the cross section is determined by x-ray absorption... 

Mononuclear Au(lll) species supported on ceria powder (averaged 46 nm) is catalytically active for CO oxidation, and would aggregate into gold clusters with even increased catalytic properties, proved by X-ray adsorption study (Aguilar-Guerrero and Gates, 2007). 

Quahtative information on the structme of the colored corrinoids in solution can be extracted rapidly from UV/Vis and CD spectra most of the spectroscopic features can be rationalized nowadays by comparison with theoretically calculated spectra. For more precise constitutional information, some of the newly developed methods of mass spectrometry allow the analysis even of the involatile Bi2-derivatives. Modem one-and two-dimensional proton, carbon, nitrogen, and phosphoms NMR spectroscopy has proven a powerful instrument for the delineation of the stmcture of diamagnetic cobalt-corrins in solution. ESR-spectroscopy has given important information on paramagnetic corrinoid Co"-complexes, whether in frozen solutions or bound in corrinoid enzymes. X-ray adsorption fine spectroscopy (EXAFS) spectroscopy and vibrational (IR and Raman) spectroscopy are other spectroscopic techniques used more frequently now in the B12 field. 

AFNOR produce the French standard NFX 11-681 for gravity sedimentation and NFX 11 -683 for variable height sedimentation using x-ray adsorption. 

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