Nucleation and growth during faceting of the platinum-covered W(111) surface

Low energy electron microscopy (LEEM) and scanning tunneling microscopy (ST M) have been used to investigate the faceting of W(111) as induced by Pt. T he atomically rough W(111) surface, when fully covered with a monolayer fil m of Pt and annealed to temperatures higher than similar to 750 K, experien ces a significant morphological restructuring: the initially planar surface undergoes a faceting transition and forms three-sided pyramids with {211} faces. When Pt is dosed onto the heated surface, the transition from planar to faceted structure proceeds through the nucleation and growth of spatial ly separated faceted region, as shown by LEEM. STM reveals the atomic struc ture of the partially faceted surface, with large planar regions, dotted by clusters of pyramids of various sizes.