Scanning tunneling microscopy study of the structure of sulfur [2(3)1/2×2(3)1/2] R 30° overlayer on rhenium (0001)

The structure of the (2(3)1/2×2(3)1/2) R30° sulfur overlayer chemisorbed on rhenium(0001) has been studied with scanning tunneling microscopy (STM). The ordered sulfur overlayer was prepared in ultrahigh vacuum and then transferred through air to an STM operating at a vacuum of 10−7 Torr. The (2(3)1/2×2(3)1/2) R30° sulfur overlayer passivates the rhenium substrate in air. STM images show the atomic structure of the overlayer unit cell to be a hexagonal ring of six sulfur atoms. Defect structures in the two-dimensional lattice of sulfur hexagons, overlayer domain boundaries and substrate dislocations were also observed.