Low-energy ion scattering measurements of quasicrystal surfaces

The technique of low-energy ion scattering spectroscopy is useful for determining the composition and structure of ordered surfaces. It can identify atoms in the topmost layer of a solid and provide real-space data about surface atom arrangement. This technique and its application to the study of quasicrystal surfaces is described using examples of the types of information that can be obtained from the ternary icosahedral alloy Al-Pd-Mn. These include surface layer and subsurface layer compositions, surface layer symmetry, interlayer spacings, and neighboring atom distances. In the case of annealed quasicrystalline Al-Pd-Mn, the surface is found to be composed primarily of Al atoms, a Pd-rich layer appears to exist just below the Al layer, and the top layers are deficient in Mn. The Al atoms at the surface exhibit local 5-fold symmetry. (C) 2002 Published by Elsevier Science B.V.