Hexagonal boron nitride (h-BN) nanostructures were grown on Ru(0001), and are very similar to those previously reported on Rh(111). They show a highly regular 12 x 12 superstructure, comprising 2 nm wide apertures with a depth of about 0.1 nm. Valence band photoemission reveals two distinctly bonded h-BN species, and X-ray photoelectron spectroscopy indicates an h-BN monolayer film. The functionality of the h-BN/Ru(0001) nanomesh is demonstrated by using this structure for the assembly of gold nanoclusters.

The structure of a single-layer graphene on Ru͑0001͒ is compared with that of a single-layer hexagonal boron nitride nanomesh on Ru͑0001͒. Both are corrugated sp 2 hybridized networks and display a band gap at the K point of their 1 ϫ 1 Brillouin zone. In contrast to h-BN/ Ru͑0001͒, g / Ru͑0001͒ has a distinct Fermi surface. Together with the band structure measurements this indicates that 0.1e per 1 ϫ 1 unit cell are transferred from the Ru substrate to the graphene. Photoemission from adsorbed xenon on g / Ru͑0001͒ identifies two Xe 5p 1/2 lines, separated by 240 meV, which reveals a corrugated electrostatic potential energy surface like on h-BN/ Rh͑111͒. These two Xe species are related to the topography of the template and have different desorption energies.

The structure of a single layer of graphene on Ru(0001) has been studied using surface x-ray diffraction. A surprising superstructure containing 1250 carbon atoms has been determined, whereby 25 x 25 graphene unit cells lie on 23 x 23 unit cells of Ru. Each supercell contains 2 x 2 crystallographically inequivalent subcells caused by corrugation. Strong intensity oscillations in the superstructure rods demonstrate that the Ru substrate is also significantly corrugated down to several monolayers and that the bonding between graphene and Ru is strong and cannot be caused by van der Waals bonds. Charge transfer from the Ru substrate to the graphene expands and weakens the C-C bonds, which helps accommodate the in-plane tensile stress. The elucidation of this superstructure provides important information in the potential application of graphene as a template for nanocluster arrays.

The structure of the commensurate (23x23) phase of graphene on Ru(0001) has been analyzed by quantitative low-energy electron diffraction (LEED)-I(V) analysis and density-functional theory calculations. The I(V) analysis uses Fourier components as fitting parameters to determine the vertical corrugation and the lateral relaxation of graphene and the top Ru layers. Graphene is shown to be strongly corrugated by 1.5 A with a minimum C-Ru distance of 2.1 A. Additionally, lateral displacements of C atoms and a significant buckling in the underlying Ru layers are observed, indicative for strong local C-Ru interactions.

We present a structural analysis of the graphene/Ru(0001) system obtained by surface x-ray diffraction. The data were fit using Fourier-series expanded displacement fields from an ideal bulk structure, plus the application of symmetry constraints. The shape of the observed superstructure rods proves a reconstruction of the substrate, induced by strong bonding of graphene to ruthenium. Both the graphene layer and the underlying substrate are corrugated, with peak-to-peak heights of (0.82 ± 0.15)Å and (0.19 ± 0.02)Å for the graphene and topmost Ru-atomic layer, respectively. The Ru-corrugation decays slowly over several monolayers into the bulk. The system also exhibits chirality, whereby in-plane rotations of up to 2.0 o in those regions of the superstructure where the graphene is weakly bound are driven by elastic energy minimization.