Angle-resolved low-energy ion scattering studies of quasicrystalline Al–Pd–Mn

We present angle-resolved low-energy ion scattering data that provide information about the composition of the topmost surface layers and atomic arrangement for a clean, 5-fold surface of a single-grain of icosahedral Al–Pd–Mn. The results show that the surface of this material has 5-fold periodicity and has a surface composition with a higher Al content than the bulk material (Al-86, Pd-13, Mn-1 versus Al-71, Pd-20, Mn-9 atom%). A predominant neighbor atom distance of 7.6±0.5 Å is calculated from the results, consistent with scanning probe measurements and bulk models of Al–Pd–Mn quasicrystals. We calculate a nearest neighbor distance of 3.0±0.2 Å. We also find that a Pd-rich layer exists just below an Al-rich outer layer, in agreement with dynamical low-energy electron diffraction calculations.