Chemical identification with non-contact atomic force microscopy of xenon atoms adsorbed on graphene on Pt(111) surfaces

摘要

Functionalization of atomic force microscopy (AFM) tips has been revealed as a powerful tool to achieve an enhanced resolution allowing to resolve intramolecular features. Such functionalization can be performed by placing different species at the apex, as Xe adatoms. Functionalized tips could be useful to investigate molecules adsorbed on graphene (Gr) surfaces, where the molecule-graphene interaction is expected to be low. In particular, the Gr/Pt(111) interface has been shown to present a low molecule-substrate interaction that keeps the properties of the adsorbed molecule close to the free-molecule state. In this work, we have investigated the adsorption of Xe on graphene on Pt(111) surfaces, a necessary previous step to the in-situ functionalization of tips with Xe on these surfaces. For this purpose, we have employed a home-made cantilever-based non-contact atomic force microscope (ncAFM) operated under ultrahigh vacuum conditions at 5 K. Our results show the growth of well-ordered Xe islands in the submonolayer regime. Then, we show that force spectroscopy can be used to distinguish these islands from the bare graphene areas without the need of atomic resolution. Finally, the extraction of single Xe adatoms from the surface and the corresponding tip functionalization have been explored.