On the origin of Ru bilayer island growth on Pt(111)

Depending on the growth temperature, Ru growth on Pt(111) proceeds preferentially via nucleation and growth of bilayer islands [Hoster HE, Iwasita T, Baumgärtner H, Vielstich W. Phys Chem Chem Phys 2001;3:337]. The physical origin for this growth behaviour was investigated by scanning tunnelling microscopy. The role of the lattice mismatch is elucidated by comparing Ru growth on Pt(111) with that on a pseudomorphic Pt monolayer film on an Ru(0001) substrate, where lattice misfit is absent. The results are interpreted using existing concepts on the adsorption properties of bimetallic surfaces, the consequences of our results and our mechanistic interpretation on the understanding of bilayer island growth in metal-on-metal epitaxy in general are discussed.