Adsorption of cobalt on the tenfold surface of d-Al72Ni 11Co17 and on the fivefold surface of i-Al 70Pd21Mn9

The adsorption behaviour of Co on the tenfold surface of d -Al 72 Ni 11 Co 17 and on the fivefold surface of i -Al 70 Pd 21 Mn 9 has been studied using scanning tunnelling microscopy (STM), Auger electron spectroscopy (AES) and low-energy electron diffraction (LEED). The analysis of a distinctive quasiperiodic LEED pattern for coverages from 3-30?ML of Co on d -Al 72 Ni 11 Co 17 suggests that the Co forms in a pseudomorphic row structure composed of domains of Fibonacci spaced rows having a periodic lattice parameter along the rows of 2.50.1. The same structure, though less well-ordered and with a larger lattice parameter, is formed on the fivefold surface of i -Al 70Pd21Mn9.