Long-Range Order Induced by Intrinsic Repulsion on an Insulating Substrate

An ordered arrangement of molecular stripes with equidistant appearance is formed upon the adsorption of 3-hydroxybenzoic acid onto calcite (10.4) held at room temperature. In a detailed analysis of the next-neighbor stripe distances measured in noncontact atomic force microscopy images at various molecular coverages, we compare the observed stripe arrangement with a random arrangement of noninteracting stripes. The experimentally obtained distance distribution deviates substantially from what is expected for a random distribution of noninteracting stripes, providing direct evidence for the existence of a repulsive interaction between the stripes. At low molecular coverage, where the average stripe distance is as large as 16 nm, the stripes are significantly ordered, demonstrating the long-range nature of the involved repulsive interaction. The experimental results can be modeled with a potential having a 1/d2 distance dependence, indicating that the observed long-range repulsion mechanism originates from...