Investigation of the twofold decagonal Al71.8Ni14.8Co13.4(10000) surface by SPA-LEED and He diffraction

The twofold decagonal Al71.8Ni14.8Co13.4(1 0 0 0 0) surface is investigated by using highly surface sensitive elastic helium atom scattering (HAS) and high resolution spot profile analyzing low energy electron diffraction (SPA-LEED). SPA-LEED and HAS data reveal diffraction patterns of the top most surface layer consistent with those of the surfaces generated by bulk truncations. Strong diffraction peaks corresponding to an 8 A periodicity are observed. These peaks are broadened along the quasiperiodic surface direction, reflecting a reduced correlation length of ≈80 A of the 8 A periodicity within the quasicrystalline planes. In addition very weak streaks corresponding to a 16 A periodicity are observed.