Near-edge fine structure techniques, surface

Near-edge X-ray NEXAFS neutron diffraction experiments on large-surface-area samples have provided important structural information on adsorbed molecules and also on surface phase transitions. A core hole is excited as in fine structure techniques (see EXAFS), Atomic structure... 

In general, several spectroscopic techniques have been applied to the study of NO, removal. X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR), nuclear magnetic resonance (NMR), extended X-ray absorption fine structure (EXAFS) and X-ray absorption near-edge structure (XANES) are currently used to determine the surface composition of the catalysts, with the aim to identify the cationic active sites, as well as their coordinative environment. 

Obviously, it is important to extend the fundamental information, obtained on the single crystal model surfaces, to the more realistic powder materials. In principle, the comparison of the electronic properties of these two systems can be achieved by using the near-edge X-ray absorption fine structure (NEXAFS) technique, which can be applied to investigate the properties of both single crystals and powder materials. The catalytic properties of the model and powder carbide materials can also be compared if the relevant reactions are carried out for both systems. 

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. 

XPEEM is a spectromicroscopy technique utilizing near edge X-ray absorption fine structure (NEXAFS) contrast. XPEEM probes the surface chemistry by detection of photoelectrons emitted from the surface. XPEEM was performed at the PEEM2 microscope at the bending magnet beamline... 

The experimental detection and quantification of surface species on in situ soil particles and other natural colloids is a difficult area of research because of sample heterogeneity, low surface concentrations, and the necessity of investigating the solid adsorbents in the presence of water. Unambiguous information can be obtained only with in situ surface spectroscopy, such as X-ray photoelectron (XPS), extended X-ray absorption fine structure (EXAFS), X-ray absorption near edge structure (XANES), inelastic electron tunnelling (lETS), and electron energy loss (EEL) spectroscopies. Recent advances in the development of non-invasive, in situ spectroscopic scanned-probe and microscopic techniques have been applied successfully to study mineral particles in aqueous suspensions (Hawthorne, 1988 Hochella and White, 1990 Bertsch and Hunter, 1998). 

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