Probing the selectivity of a nanostructured surface by xenon adsorption.

Surface-supported molecular self-assembly with the goal to produce highly ordered, functional supramolecular nanostructures are often realized using nanopatterned surfaces, which exhibit long range - ideally periodic - modulations of the molecule adsorption properties. To elucidate the physical origins of the site-specific adsorption properties of such a nanopatterned substrate, we investigated the temperature-dependent microscopic structure and the dynamics of adsorbed Xe at different temperatures on single-sheet h-BN on a Rh(111) nanomesh. In combination with molecular dynamics simulations we show that the site-specific adsorption arises from two different interactions of similar magnitude with respect to their lateral variations. The first can be attributed to a van der Waals type interaction, whereas the second originates from lateral variation of the electrostatic surface potential and is of polarization type. Both types lead to an adsorption energy minimum at the rim of the nanomesh pore and are therefore responsible for stabilizing dynamic and static Xe rings in these pores. The insight into this interplay of interactions should pave the way to gain a more general knowledge on such site-specific adsorption processes.