Self-Guided Growth of Electronically Decoupled C-60 on Graphene on Rh(110)

The authors report on the behavior of C-60 molecules adsorbed on graphene (Gr) monolayers grown on Rh(110), studied by means of scanning tunneling microscopy and spectroscopy under ultra-high vacuum conditions. Fullerene molecules form a well-ordered close packed hexagonal layout with an intermolecular distance of approximate to 1 nm. As demonstrated from the experimental data, the molecular packing direction of C-60 is locally close to being aligned with the quasi-1D moire patterns formed by graphene on the metal support. Moreover, for certain orientations of graphene on Rh(110), the underlying moire pattern appears superimposed on the molecular assembly. However, the analysis of the highest occupied molecular orbital and the lowest unoccupied molecular orbital structures and the differential conductance curves of C-60 on Gr/Rh(110) suggest a weak molecule-substrate interaction, similar to other 2D material/metal interfaces. All these observations can imply that the moire structures of Gr/Rh(110) play a central role in the arrangement of C-60, but without modifying its electronic properties, which makes this Gr/Rh(110) system a singular platform for C-60 adsorption. Complementarily, the structural properties of multilayer growth of C-60 on Gr/Rh(110) are also investigated.