Structural Characterization of Surface and Morphology of Materials Using X-ray Scattering

Abstract

Various reactions through the solid—vapor, liquid—vapor and solid—liquid interfaces are known to play a significant role in many chemical and metallurgical processes. Therefore, there is an increasing need for the structural information of these interfaces. A number of experimental data are available, for example the surface tension of liquid metals and oxides using the maximum bubble method or solid—liquid interfacial energy of metals determined from dihedral angle measurements [1]. However, structural studies of the interface of liquids and surface layer of solids are still limited and knowledge of interfaces at the atomic level is far from complete. Knowledge of the structural features of surface or morphology of materials is also a prerequisite to various applications originating from physics, chemistry and engineering. This demand has been satisfied by the availability of a large variety of surface specific experimental methods. This includes electron diffraction methods such as LEED and RHEED, frequently used for surface analysis because of their inherent surface sensitivity due to the strong interaction between electrons and atoms. The electron diffraction method is undoubtedly recognized as a powerful tool for characterizing the surface layer of materials and works well. Nevertheless, we should mention that its quantitative analysis is not so easy due to difficulties arising from the dynamical effect in the diffraction process. Another limitation of this method is that some tedious experimental conditions such as ultra-high vacuum and elaborate sample preparations are essentially required.