X-RAY NEAR EDGE SPECTROSCOPY

The shape of the edge itself examined by XANES (X-ray near-edge spectroscopy) can be employed to reveal information on d-band vacancy concentration vs. treatment. The oscillations at energies above the edge (EXAFS) ctui provide information on near-neighbor atom spacing tuid some limited information on the chemical environment. As we will show, the best way to use such tools is to use several at once, rather them only one. 

Some recent investigations have applied advanced spectroscopic methods to nondestructively probe the associations between Fe oxides and other metals in Fe plaque with unprecedented spatial resolution. These techniques include x-ray fluorescence microscopy (XRF) and x-ray near-edge spectroscopy (XANES). Hansel et al. (2001) investigated the sequestration of Pb, Mn, and Zn to Fe plaque on the wetland plant Phalaris arundinacea (reed canarygrass) from a mine waste-contaminated site. They found that Pb was concentrated within the Fe plaque. However, extended x-ray absorption fine structure (EXAFS) data indicated that the Pb was not directly coordinated with the Fe oxides but was probably bound to organic matter in the form of a biofilm. Mn and Zn were also associated with Fe plaque, but chemically they appeared to exist as discrete carbonates. This work on Pb contrasts somewhat with that of Ye et al. (1998), who reported that Pb was not bound significantly to Fe plaque in Typha. 

Transpassive dissolution of Cr and sputter deposited Cr oxides studied by in situ X-ray near edge spectroscopy. J Electrochem Soc 143 3997 005. doi 10.1149/l.1837327... 

Surface analytical techniques such as Auger electron spectroscopy (27), X-ray photoelectron spectroscopy (28), and secondary-ion mass spectrometry (29) have been used to study LB films. Synchrotron radiation is a particularly powerful probe enabling X-ray near-edge structure and extended X-ray absorption fine structure to be measured. Angle-resolved photoemission studies (30) confirmed the existence of a one-dimensional energy band along the (CH2)jc chain in a fatty acid salt film. 

In many materials problems, for example at surfaces or interfaces, the chemical composition and nuclear coordinates are not fully known. Indeed, any information which can be obtained by theory on these basic structural properties will be useful, in conjunction with experiment. Spatially Resolved Electron Energy Loss Spectroscopy (SREELS), X-ray near-edge absorption (XANES) and emission, Mossbauer spectra, etc. provide site-specific probes which can be combined with theory to help resolve structures. 

XAFS - X-ray absorption edge spectroscopy XANFS - X-ray absorption near edge structure XAS - X-ray absorption spectroscopy Xg - a high-energy intermediate... 

Amorphous carbon films may be broadly classified as (i) amorphous carbon films, a-C films, deposited from carbon-containing gases with low or zero hydrogen content [72] and (ii) hydrogenated carbon films, a-C H films, formed from hydrocarbon-containing gases [73,74]. Both types of film contain different amounts of sp and sp bonded carbon. The amount of sp bonded carbon can be estimated from X-ray absorption near edge spectroscopy,... 

X-ray absorption near-edge spectroscopy (XANES) suggests that, in most of the enzymes, the reduction to Ni-SI also implies a change in the coordination number of the Ni ion from 5 to 6 (74). 

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. 

The most prevalent technique exploiting synchrotron radiation is X-ray absorption spectroscopy (XAS, also called X-ray absorption fine structure, XAFS). Two related types of experiments are conducted X-ray absorption near-edge spectroscopy (XANES), which probes the initial absorption edge and related nearby structure, and... 

Extended X-ray Absorption Fine-Structure/X-ray Absorption Near-Edge Spectroscopy... 

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