X-ray absorption fine structure. See

NEXAFS Near-edge X-ray absorption fine structure (see XANES)... 

Once the organometallic species is bound to a surface, many of the usual solution characterization methods no longer apply. A combination of EXAFS (extended X-ray absorption fine structure see Chapter 16), solid-state NMR, and IR spectroscopy, however, can often give sufficient infonnation to characterize the surface-bound species. 

For bulk structural detemiination (see chapter B 1.9). the main teclmique used has been x-ray diffraction (XRD). Several other teclmiques are also available for more specialized applications, including electron diffraction (ED) for thin film structures and gas-phase molecules neutron diffraction (ND) and nuclear magnetic resonance (NMR) for magnetic studies (see chapter B1.12 and chapter B1.13) x-ray absorption fine structure (XAFS) for local structures in small or unstable samples and other spectroscopies to examine local structures in molecules. Electron microscopy also plays an important role, primarily tlirough unaging (see chapter B1.17). 

EXAFS is part of the field of X-ray absorption spectroscopy (XAS), in which a number of acronyms abound. An X-ray absorption spectrum contains EXAFS data as well as the X-ray absorption near-edge structure, XANES (alternatively called the near-edge X-ray absorption fine structure, NEXAFS). The combination of XANES (NEXAFS) and EXAFS is commonly referred to as X-ray absorption fine structure, or XAFS. In applications of EXAFS to surface science, the acronym SEXAFS, for surface-EXAFS, is used. The principles and analysis of EXAFS and SEXAFS are the same. See the article following this one for a discussion of SEXAFS and NEXAFS. 

Quantitative data on local structure can be obtained via an analysis of the decaying slope next to the absorption edge. The absorption of an X-ray photon boosts a core electron up into an unoccupied band of the material which, in a metal, is the conduction band above the Fermi level. Electrons in such a band behave as if nearly free and no fine structure would be expected on the absorption tail . However, fine structure is observed up to 500 to 1000eV above the edge (see Figure 2.73(b)). The ripples are known as the Kronig fine structure or extended X-ray absorption fine structure (EX AFS). 

Surface-enhanced resonance Raman scattering (SERRS), 21 327-328 advantage of, 21 329 Surface Evolver software, 12 11 Surface excess, 24 135, 136 Surface extended X-ray absorption fine structure (SEXAFS), 19 179 24 72 Surface filtration, 11 322-323 Surface finish(es). See also Electroplating in electrochemical machining, 9 591 fatigue performance and, 13 486-487 Surface finishing agents, 12 33 Surface force apparatus, 1 517 Surface force-pore flow (SFPF) model,... 

X-ray imaging, selenium in, 22 101. See also Extended X-ray absorption fine structure (EXAFS) analysis X-ray imaging techniques, 16 504 X-ray imaging tests, 26 440 X-ray-induced X-ray emission, 24 109 X-ray instruments, 26 411... 

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