The Calcite(10-14) Surface: A Versatile Substrate for Molecular Self-Assembly

This thesis presents a detailed and successful study of molecular self-assembly on the calcite CaCO3(1014) surface. One reason for the superior applicability of this particular surface is given by reflecting the well-known growth modes. Layer-by-layer growth, which is a necessity for the formation of templated 2D molecular structures, is particularly favoured on substrates with a high surface energy. The CaCO3(1014) surface is among those substrates and, thus, most promising.All experiments in this thesis were performed using the NC-AFM technique under ultrahigh vacuum conditions. The acquisition of drift-free data became in this thesis possible owing to the herein newly developed atom-tracking system. This system features a lateral tippositioning precision of at least 50 pm. Furthermore, a newly developed scan protocol was implemented in this system, which allows for the acquisition of dense 3D data under roomtemperature conditions. An entire 3D data set from a CaCO3(1014) surface consisting of 85 85 500 pixel is discussed.The row-pairing and (2 1) reconstructions of the CaCO3(1014) surface constitute most interesting research subjects. For both reconstructions, the NC-AFM imaging was classified to a total of 12 contrast modes. Eight of these modes were observed within this thesis, some of them for the first time. Together with literature findings, a total of 10 modes has been observed experimentally to this day. Some contrast modes presented themselves as highly distancedependent and at least for one contrast mode, a severe tip-termination influence was found. Most interestingly, the row-pairing reconstruction was found to break a symmetry element of the CaCO3(1014) surface. With the presence of this reconstruction, the calcite (1014) surface becomes chiral. From high-resolution NC-AFM data, the identification of the enantiomers is here possible and is presented for one enantiomer in this thesis.Five studies of self-assembled molecular structures on calcite CaCO3(1014) surfaces are presented. Only for one system, namely HBC/CaCO3(1014), the formation of a bulk structure was observed. This well-known occurence of weak molecule-insulator interaction hinders the investigation of two-dimensional molecular self-assembly. It was, however, possible to force the formation of an island phase for this system upon following a variable-temperature preparation. For the C60/CaCO3(1014) system it is most notably that no branched island morphologies were found. Instead, the first C60 layer appeared to wet the calcite surface.