Structure and reactivity of Bi alltiotropes on the fivefold icosahedral Al-Pd-Mn quasicrystal surface

Abstract

The growth of Bi on a pseudomorphic Bi monolayer on the fivefold surface of the icosahedral Al-Pd-Mn quasicrystal has been investigated using low energy electron diffraction and scanning tunnelling microscopy. Initially randomly oriented pseudocubic islands are formed with a preference for an even number of layers. Subsequently a morphological transformation takes place to hexagonal Bi islands, which align along high symmetry directions of the substrate. The Bi flux is found to have a strong effect on which island structure is preferred. When C 60 is adsorbed on the three different allotropes of Bi present in this system, hexagonal C 60 islands are formed in each case. On the pseudocubic and hexagonal islands, the C 60 islands are aligned with the substrate. We discuss the energetic, kinetic and geometrical factors which influence the morphological transformation referred to above.