Single Molecule Force Spectroscopy (Invited)

Recently, intramolecular resolution is studied on a variety of molecules. A further challenge is the manipulation of molecules on surfaces, including the controlled rotation, which means that the direction of rotation of the molecule can be chosen by the experimentalist [1]. The control of the probing tip is of central importance for a quantitative understanding of nc-AFM imaging and force spectroscopy. Progress has been made by a variety of preparation procedures: sputtering, indentation or pick-up of molecules, such as CO. The attachement of a single molecule to the end of the tip is shown for the case of a functionalized porphyrin, which can used as a stable probing tip for imaging in the attractive as well as the repulsive regime. 

[1] R. Pawlak, S. Fremy, S. Kawai, T. Glatzel, H. Fang, L.-A. Fendt, F. Diederich, and E. Meyer , Directed rotations of single porphyrin molecules controlled by localized force spectroscopy, ACS Nano, 6, (2012), 6318–6324