Structural identification of graphene films and nanoislands on 6H-SiC(0001) by direct height measurement.

By combining non-contact atomic force microscopy (nc-AFM) and Kelvin probe microscopy (KPFM) in ultra high vacuum environment (UHV), we directly measure the height and work function of graphene monolayer on the Si-face of 6H-SiC(0001) with a precision that allows us to differentiate three different types of graphene structures : zero layer graphene (ZLG), Quasi free-standing monolayer graphene (QFMLG) and bilayer graphene (BLG). The height and work function of ZLG are 2.62 ± 0.

An NC-AFM and KPFM study of the adsorption of a triphenylene derivative on KBr(001).

The adsorption on KBr(001) of a specially designed molecule, consisting of a flat aromatic triphenylene core equipped with six flexible propyl chains ending with polar cyano groups, is investigated by using atomic force microscopy in the noncontact mode (NC-AFM) coupled to Kelvin probe force microscopy (KPFM) in ultrahigh vacuum at room temperature. Two types of monolayers are identified, one in which the molecules lie flat on the surface (MLh) and another in which they stand approximately upright (MLv). The Kelvin voltage on these two structures is negatively shifted relative to that of the clean KBr surface, revealing the presence of surface dipoles with a component pointing along the normal to the surface.

Self-assembly of fivefold-symmetric molecules on a threefold-symmetric surface.

Buckybowls: The adsorption of penta-tert-butylcorannulene, a molecule with fivefold symmetry, on Cu(111), a surface with threefold symmetry, is investigated by scanning tunneling microscopy complemented by structure calculations. The symmetry mismatch is resolved by the formation of threefold-symmetric subunits consisting of three molecules, which combine with single molecules to form a nearly perfect filling of the plane (see picture).

Development of UHV dynamic nanostencil for surface patterning.

A dynamic nanostencil system based on a movable atomic force microscopy (AFM) cantilever-borne mask has been developed in ultrahigh vacuum environment. This system is conceived to offer an outstanding nanopatterning capability of nanometer precision as well as in situ AFM characterization with a large scanning range. Evaporation experiments in both static and dynamic mode have been performed successfully on this system, and some crucial technical problems of stencilling technique such as resolution and clogging are investigated.