Monitoring molecular motion and structure near defect with STM

The diffusion dynamics and enantiomeric structure of the alkyl-substituted isophthalic acid adlayer physisorbed on highly oriented pyrolytic graphite (HOPG) have been investigated in the vicinity of defect by scanning tunneling microscopy (STM). Through molecular motion and reorientation, the defect in the monolayer is filled and an ordered two-dimensional (2D) packing appears. Moreover, an enantiomeric structure is also observed. These findings can be explained by the role of molecular mobility and the cooperation of molecule/molecule and molecule/substrate interactions. The result provides experimental evidences for molecular diffusion and chirality in two dimensions.