Precise Determination of Molecular Adsorption Geometries by Room Temperature Non-Contact Atomic Force Microscopy

Abstract High resolution force measurements of molecules on surfaces, in non-contact atomic force microscopy, are often only performed at cryogenic temperatures, due to needing a highly stable system, and a passivated probe tip (typically via CO-functionalisation). Here we show for the first time, a reliable protocol for acquiring three-dimensional force map data over both single organic molecules and assembled islands of molecules, at room temperature. Isolated cobalt phthalocyanine and islands of C60 are characterised with submolecular resolution, on a passivated silicon substrate (B:Si(111)-(√3×√3)R30°). Geometries of cobalt phthalocyanine are determined to a ∼10 pm accuracy. For the C60, the protocol is sufficiently robust that areas spanning 10nm×10nm are mapped, despite the difficulties of room temperature operation. These results provide a proof-of-concept for gathering high-resolution three-dimensional force maps of networks of complex, non-planar molecules on surfaces, in conditions more analogous to real-world application.