Surface analytical techniques structure EXAFS

The interfacial region of a metal up to the IHP has been considered as an electronic molecular capacitor, and this model has explained many experimental results with success20. Another important model is the jellium model21 (Fig. 3.13fo). From an experimental point of view, the development of in situ infrared and Raman spectroscopic techniques (Chapter 12) to observe the structure, and the calculation of the bond strength at the electrode surface can better elucidate the organization of the double layer. Other surface analytical techniques such as EXAFS are also valuable. 

Surface analytical techniques. A variety of spectroscopic methods have been used to characterize the nature of adsorbed species at the solid-water interface in natural and experimental systems (Brown et al, 1999). Surface spectroscopy techniques such as extended X-ray absorption fine structure spectroscopy (EXAFS) and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) have been used to characterize complexes of fission products, thorium, uranium, plutonium, and uranium sorbed onto silicates, goethite, clays, and microbes (Chisholm-Brause et al, 1992, 1994 Dent et al, 1992 Combes et al, 1992 Bargar et al, 2000 Brown and Sturchio, 2002). A recent overview of the theory and applications of synchrotron radiation to the analysis of the surfaces of soils, amorphous materials, rocks, and organic matter in low-temperature geochemistry and environmental science can be found in Fenter et al (2002). 

Recent in situ applications of different surface analytical techniques such as EXAFS, GKS, STM, AFM, etc., opened a new window to get direct information on the structure of Me UPD adlayers at an atomic level. Structural aspects of UPD adlayers based on both electrochemical and modem surface analytical results will be discussed in detail in the next section. 

In-situ physical techniques. In-situ spectroscopic methods (particularly infrared spectroscopy) are now almost routine, but no single analytical technique is sufficient to solve the problem of ambiguity of structure and reactivity a combination of techniques should be applied. The use of EXAFS has developed rapidly, and a similar advance in solid-state NMR is anticipated. Both are amenable to in-situ studies, in contrast to the majority of surface-science techniques. 

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