Gallenene, an analogue of graphene composed of gallium, is epitaxially grown on Si(1 1 1) surface and studied by low temperature scanning tunneling microscopy (LT-STM). The STM images display that the buffer layer has a superstructure with respect to the substrate lattice and the gallenene layer has a hexagonal honeycomb structure. The scanning tunneling spectra (STS) of the gallenene show that it behaves as a metallic layer. First-principles calculations give the proposed configuration. Our results provide a method to synthesize the gallenene and shed important light on the growth mechanism of it.

Water on solid surfaces is essential for a wide range of scientific and technological processes. Previous studies reveal that water molecules on metal surfaces usually form layered structures with a honeycomb hydrogen-bond network, similar to the basal plane of hexagonal ice I h . Here we report a new type of monolayer ice grown on graphite surface at low temperature with subsequent annealing. High-resolution STM images reveal that the monolayer ice is composed of cyclic water hexamers without sharing edges. Moreover, the monolayer ice exhibits multiple orientations relative to the graphite lattices, resulting in various moiré patterns. First-principles calculations reveal that the moiré superstructures contain both tilted and planar water hexamers, corresponding to the horseshoe-like and flat water rings observed in the STM images. All water molecules within the monolayer are saturated by four hydrogen bonds, and the strong intralayer bonding gives rise to a high stability of the monolayer ice.

No abstract

We report an ultra-high vacuum low-temperature scanning tunneling microscopy (STM) study of the C60 monolayer grown on Cd(0001). Individual C60 molecules adsorbed on Cd(0001) may exhibit a bright or dim contrast in STM images. When deposited at low temperatures close to 100 K, C60 thin films present a curved structure to release strain due to dominant molecule–substrate interactions. Moreover, edge dislocation appears when two different wavy structures encounter each other, which has seldomly been observed in molecular self-assembly. When growth temperature rose, we found two forms of symmetric kagome lattice superstructures, 2 × 2 and 4 × 4, at room temperature (RT) and 310 K, respectively. The results provide new insight into the growth behavior of C60 films.

No abstract