Self-organized molecular-sized, hexagonally ordered SnOx nanodot superlattices on Pt(111)

Complete oxidation of the (√3×√3)R30° Sn/Pt(111) surface alloy or submonolayer amounts of Sn adatoms on Pt(111) under ultrahigh vacuum conditions, forms a highly ordered, lateral superlattice of SnOx islands on the Pt(111) substrate. The island superstructure exhibits a sharp (5×5) low energy electron diffraction pattern. Scanning tunneling microscopy images show islands arranged in a hexagonal lattice, uniformly distributed over the whole sample. This island array is thermally stable up to 1050 K. The coincidence of the island periodicity with a multiple of the supporting substrate, and the same hexagonal symmetry of islands and substrate, suggests a strong island–substrate interaction. We propose that the island formation results from the breakup of a strained SnOx adlayer.