Surface X-Ray Diffraction SXD

Instrumentation. The electrochemical cells described in the preceding section can be used. A cell design with a significantly reduced radiation absorption of the electrolyte solution film as used for specular X-ray reflectivity measurements (see description below Fig. 6.10) can also be used. Electrode potentials are selected based on standard electrochemical experiments (e.g. cyclic voltammetry) with respect to well-defined changes of the electrode-solution interface (e.g. potential steps between potentials of complete desorption and maximum adsorption). Control of the potentiostat and the X-ray diffractometer as well as data acquisition, storage and manipulation are done with a suitably programmed computer. 

Typical examples include studies of the underpotential deposition of various metals on metallic substrates. The structure of the upd-layer [33, 34], the position of adsorbed anions and water molecules on top of the upd-layer and the respective bond angles and lengths could be elucidated [35, 36]. Surface reconstruction caused by weakly adsorbed hydrogen [37], surface expansion effects of low-index platinum and gold surfaces correlated with adsorption/desorption of solution species [38] and 

The slightly gradual distinction implies possible overlap between both groups of methods. 

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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... 

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