Benzene Adsorption on Rh(111): A New Perspective on Intermolecular Interactions and Molecular Ordering

Abstract

The adsorption of benzene on the Rh(111) substrate was investigated through scanning tunneling microscopy imaging and density functional theory calculations. Experiments were carried out at various surface coverages, with the amount of benzene adsorbed determined to influence the molecular adsorption site, the intermolecular interactions, and the interaction between the molecule and the substrate. At a sub-monolayer coverage of the surface, the molecules are disordered and kept apart by a strong interadsorbate repulsion, with a preference for the molecule to adsorb on a threefold hexagonally close-packed hollow site. At high coverage, the preferred adsorption site becomes the twofold symmetric bridge site, whether as part of the two dense ordered structures that form at high coverage ((2√3 × 3)rect or (√19 × √19)R23.4°) or as part of the disordered array of benzene molecules, which are arranged in formations which resemble the “building blocks” of the ordered overlayers. Despite the adsorption energy for ...