Ordering of adsorbed species on quasicrystal surfaces

Abstract

We present an overview of experimental studies of the structure of adsorbed atomic and molecular species on quasicrystal surfaces with a particular focus on those systems where quasiperiodic ordering of the adsorbate structure occurs. Atomic adsorption is illustrated with examples from studies of Fe and Gd adsorption on the five-fold surface of i-Al–Pd–Mn. Overlayer structure is correlated with several physical parameters to identify trends. It is concluded that the chemical properties of the adsorbate (metallic radius, electronegativity, melting temperature) are important indicators of quasiperiodic structuring of the adsorbate system. These correlations allow predictions of those elements likely to yield pseudomorphic overlayers. Structural effects upon molecular adsorption on clean quasicrystal surfaces have been less successful. A new approach to ordered molecular adsorption is described and illustrated for C₆₀ adsorption on a Pb monolayer film on the ten-fold surface of d-Al–Ni–Co.

Keywords:

• quasicrystalline alloys
• quasicrystals
• scanning probe microscopy
• STM
• surfaces

Acknowledgements

The UK Engineering and Physical Sciences Research Council (EPSRC) grant number EP/D05253X/1 and the European Union Network of Excellence ‘Complex metallic alloys’ Grant number NMP3-CT-2005-500145 are thanked for financial support. T.A. Lograsso, A.R. Ross, C.J. Jenks (Ames Laboratory, Iowa, USA) and I.R. Fisher (currently at Stanford University, California, USA) are acknowledged for providing the i-Al–Pd–Mn and d-Al–Ni–Co samples.