STM investigation of atomic-scale structures of Ag/Au(111) surface.

An atomic-level understanding of Ag-Au heterostructures is crucial for elucidating the catalytic and plasmonic properties of Ag-Au bimetallic nanostructures, as well as their potential applications. In this study, we investigated the surface structures of Ag formed on an Au(111) surface using scanning tunneling microscopy (STM) to gain atomic-level insight. When the substrate temperature during Ag deposition was at room temperature, two distinct ordered structures were observed on the Au(111) surface: island structures on terraces and (√3 × √3)R30° periodic structures near step edges. In contrast, the island structures did not form under the elevated substrate-temperature conditions up to 150 °C. Atomic-resolution STM images revealed that these structures consist of Ag adatoms and exhibit the periodicities with respect to the underlying Au(111) lattice that are distinct from those of previously reported epitaxial Ag(111) film structures.