Chains of Na atoms and dicyanovinyl-quinquethiophene (DCV5T-Me2) molecules with ionic bonds form a superlattice on Au(111). Through a detailed analysis of the interchain distances obtained from scanning tunneling microscopy images at various molecular coverages, we found that the chain arrangement substantially deviates from a random distribution of noninteracting chains. Instead, the distribution of chain spacings provides evidence for the existence of an interchain long-range repulsive potential. Furthermore, the experimental results can be modeled by a repulsive potential with a 1/d distance dependence, characteristic of Coulomb interactions. Density functional theory calculations of free-standing molecular chains reveal a charge depletion at the periphery of the chains, which is attributed to the intrinsic polar property of the molecule and is responsible for the long-range repulsion.
@article{arxiv.2108.05189,
title = {Metal-Organic Superlattices Induced by Long-Range Repulsive Interactions on a Metal Surface},
author = {Zechao Yang and Christian Lotze and Katharina J. Franke and Jose I. Pascual},
journal= {arXiv preprint arXiv:2108.05189},
year = {2021}
}