Quantitative analysis of long-range interactions between adsorbed dipolar molecules on Cu(111).

Highly dispersed superstructures of a dipolar iridium complex are formed on a Cu(111) surface. We show that the dilute superstructures with density-controlled intermolecular separations are stabilized by the strong and long-range repulsive intermolecular interactions. The repulsive intermolecular interactions are quantitatively evaluated by using low-temperature scanning tunneling microscopy, which are characterized by the surface-enhanced dipole-dipole interactions.