STM investigation of alkylated thiotriphenylene monolayers at the solid-liquid interface: Structure and dynamics

We describe a STM investigation of the structure and dynamics of alkylated thiotriphenylene monolayers at the solid-liquid interface. This discotic system was found to pack into two coexisting structural motifs on the basal plane of graphite. The interpretation of the intra-molecular contrast in the STM images showed a large contribution of electronic levels localized on the sulfur atoms bridging the conjugated core with the aliphatic side-chains. The temporal evolution of domain boundaries in a polycrystalline monolayer, explored by recording series of subsequent STM images, revealed an Ostwald ripening phenomenon, namely coarsening in two-dimensional molecular polycrystals.