Final Report Summary - CEMAS (Controlling and Exploring Molecular Systems at the Atomic Scale with Atomic Force Microscopy) The CEMAS project focused on the further development and use of the Atomic Force Microscopy (AFM) technique to study the properties of single molecules at the atomic scale. Techniques were developed and demonstrated that allow resolving the molecular structure, the intramolecular charge distribution [1], different bond orders [2], identifying heteroatoms and specific molecular groups. A detailed understanding of the important role of tip functionalization in high resolution AFM imaging was achieved by studying a series of different tip terminations experimentally and theoretically. In addition, atomic/molecular manipulation was used for single molecule chemistry including bond breaking and formation. Most of the studies were performed on insulating films, which allowed us to control the charge state of molecules and to prepare and study reactive compounds by producing radicals, such as arynes [3], diynes [4] and triangulene. Furthermore, it was possible to control and follow single electron lateral charge transfer between individual molecules [5]. This work was performed on insulating films (NaCl) of thickness above 5 nm to block charge transfer to an underlying metallic substrate. For future fabrication of charge storing devices in the 100nm regime, we build a novel low temperature stencil mask instrument operating under ultrahigh vacuum conditions. As an important application, chemical structure identification combining AFM high resolution imaging and STM orbital imaging was demonstrated ranging from single natural product molecules up to complex mixtures such as asphaltenes [6]. [1] F. Mohn et al., Nature Nanotechnology 7, 227 (2012)[2] L. Gross et al., Science 337, 1326 (2012)[3] N. Pavlicek et al., Nature Chemistry 7, 623 (2015)[4] B. Schuler et al., Nature Chemistry 8, 220 (2016) [5] W. Steurer et al., Nature Communications 6, 8353 (2015)[6] B. Schuler et al., J. Am. Chem. Soc. 137, 9870 (2015)
