X-ray surface diffraction

Because x-rays are particularly penetrating, they are very usefiil in probing solids, but are not as well suited for the analysis of surfaces. X-ray diffraction (XRD) methods are nevertheless used routinely in the characterization of powders and of supported catalysts to extract infomration about the degree of crystallinity and the nature and crystallographic phases of oxides, nitrides and carbides [, ]. Particle size and dispersion data are often acquired with XRD as well. 

Samant, M.G., Brown, C.A. and Gordon, J.G. (1992) Formation of an Ordered Self-Assembled Monolayer of Docosaneselenol on Gold(lll). Structure by Surface X-ray Diffraction. Langmuir, 8, 1615-1618. 

FIGURE 27.9 (a) Voltammetry curve for the UPD of TI on Au(l 11) in 0.1 M HCIO4 containing ImMTlBr. Sweep rate 20mV/s. The in-plane and surface normal structural models are deduced from the surface X-ray diffraction measurements and X-ray reflectance. The empty circles are Br and the filled circles are Tl. (b) Potential-dependent diffraction intensities at the indicated positions for the three coadsorbed phases. (From Wang et al., 1998, with permission from Elsevier.)... 

The structure of alumina on NiAl(l 1 0) was the subject of a surface X-ray diffraction study by Stierle et al. [46]. The model derived by Stierle et al. from the analysis of the X-ray diffraction data was based on a strongly distorted double layer of hexagonal oxygen ions, where the Al ions are hosted with equal probability on octahedral- and tetrahedral-coordinated sites the resulting film structure was closely related to bulk k-A1203. An attractive feature of Stierle s model was that it provided a natural explanation of the domain structure of the alumina overlayer, which is induced by a periodic row matching between film and substrate lattices. However, as pointed out recently by Kresse et al. [47], this structure model has two bonds with... 

Figs. 2-iO Laue surface X-ray diffraction photographs for three low index surfaces of Pt single crystals. (C) PtdOO)... 

Adsorption and oxidation of NO adlayers on Pt(lll) was studied by using in situ surface X-ray diffraction and ex situ X-ray photoemission spectroscopy [86]. Molecular adsorption of NO was observed independently of the preparation of the adlayer. 

Ocko etal. [57, 58] have studied adsorption of bromide on Au(lOO) using in situ surface X-ray diffraction (SXD) in combination with electrochemical measurements. Low surface excess of bromide ions at Au(100)-(hex) caused a lifting of the... 

XRD X-Ray Diffraction X-ray diffraction has been carried out at extreme glancing angles of incidence where total reflection assures surface sensitivity. This provides structural information that can be interpreted by well-known methods. An extremely high x-ray flux is required to get useful data from single crystal surfaces. Bulk x-ray diffraction is used to determine the structure of organo-metallic clusters, which provide comparisons to molecules adsorbed on surfaces. X-ray diffraction has also given structural information on large surface-area samples. 

Robinson IK, Tweet DJ (1992) Surface x-ray diffraction. Rep Prog Phys 55 599... 

Saint-Lager MC, Jugnet Y, Dolle P, Piccolo L, Baudoing-Savois R, Bertolini JC, Bailly A, Robach O, Walker C, Ferrer S (2005) Pd8Ni92(l 10) surface structure from surface X-ray diffraction. Surface evolution under hydrogen and butadiene reactants at elevated pressure. Surf Sci 587 229... 

Robinson IK, Eng PJ, Schuster R (1994) Origin of the surface sensitivity in surface X-ray diffraction Acta Physica Polonica A 86 513-520... 

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