INSIGHT INTO THE SURFACE STRUCTURE QUASICRYSTALLINE Al-Pd-Mn

Cynthia J. Jenks

Ames Laboratory, Iowa State University, Ames, IA 50011 USA

Angle-resolved low energy ion scattering is one of a few techniques that is truly sensitive to the topmost layer of a surface. Information about surface symmetry, atomic distances and composition can be obtained. We have used this technique to examine the five-fold surface of icosahedral Al₇₁Pd ₂₀Mn₉. Our results are consistent with the surface maintaining five-fold symmetry after sputtering followed by annealing. We find that the topmost surface layer is > 85 atomic % aluminum. A predominant neighbor atom distance of 7.6 ± 0.5 ≈ and a nearest neighbor distance of 3.0 ± 0.1 ≈ are calculated from our results. These results are consistent with previous low energy electron diffraction intensity versus voltage (LEED-IV) calculations, recently published scanning tunneling microscopy results and a bulk model of Al-Pd-Mn quasicrystals.