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The initial growth of 3,4,9,10-perylene-tetracarboxylic-dianhydride (PTCDA) was analysed. Ultrathin films with coverages of up to two layers were prepared on a (111) orientated copper single crystal by means of vapour deposition in an ultrahigh-vacuum chamber. The films were characterized in situ by scanning tunnelling microscopy (STM). Within the first layer, two different structures were found. Both exhibit a herringbone-like arrangement of the molecules, which is also found in the (102) plane of the α and β bulk phases. The twodimensional unit cell is given by two molecules which are rotated by about 90 • . As an effect of the interaction with the substrate, a voltage-dependent moiré pattern was observed for one of these phases. For the second layer, a herringbone phase was found that is denser than the phases of the first layer but less dense than the bulk phases.

GXSM is a full featured and modern scanning probe microscopy (SPM) software. It can be used for powerful multidimensional image/data processing, analysis, and visualization. Connected to an instrument, it is operating many different flavors of SPM, e.g., scanning tunneling microscopy and atomic force microscopy or, in general, two-dimensional multichannel data acquisition instruments. The GXSM core can handle different data types, e.g., integer and floating point numbers. An easily extendable plug-in architecture provides many image analysis and manipulation functions. A digital signal processor subsystem runs the feedback loop, generates the scanning signals, and acquires the data during SPM measurements. The programmable GXSM vector probe engine performs virtually any thinkable spectroscopy and manipulation task, such as scanning tunneling spectroscopy or tip formation. The GXSM software is released under the GNU general public license and can be obtained via the internet.

The two planar organic molecules copper-phthalocyanine (CuPc) and 3,4,9,10-perylene-tetracarboxylic-dianhydride (PTCDA) are found to form an ordered mixed monolayer on Cu(111). The layers have been prepared by exposing the surface to an equivalent of a little bit more than half of a monolayer of CuPc and the same amount of PTCDA followed by thermal annealing. The investigations by scanning tunneling microscopy reveal regular patterns with a commensurate unit cell which contains one CuPc and two PTCDA molecules.

Quinacridone (QA) has recently gained attention as an organic semiconductor with unexpectedly high performance in organic devices. The strong intermolecular connection via hydrogen bonds is expected to promote good structural order. When deposited on a substrate, another relevant factor comes into play, namely the 2D-chirality of the quinacridone molecules adsorbed on a surface. Scanning tunneling microscopy (STM) images of monolayer quinacridone on Ag(111) deposited at room temperature reveal the formation of quasi-one-dimensional rows of parallel quinacridone molecules. These rows are segmented into short stacks of a few molecules in which adjacent, flat-lying molecules of a single handedness are linked via hydrogen bonds. After annealing to a temperature of T = 550–570 K, which is close to the sublimation temperature of bulk quinacridone, the structure changes into a stacking of heterochiral quinacridone dimers with a markedly different intermolecular arrangement. Electron diffraction (LEED) and photoelectron emission microscopy (PEEM) data corroborate the STM findings. These results illustrate how the effects of hydrogen bonding and chirality can compete and give rise to very different (meta)stable structures of quinacridone on surfaces.

The organic molecule 3,4,9,10-perylene-tetracarboxylic dianhydride (PTCDA) was studied by means of scanning tunneling microscopy (STM) on thin insulating NaCl films grown on a Cu(111) single crystal. The deposition of approximately two monolayers (ML) of sodium chloride onto a Cu(111) substrate at a sample temperature of about 350 K causes a rather rough growth of (100)-oriented NaCl islands up to a local height of 4 ML. For submonolayer coverages (0.1 and 0.4 ML) of PTCDA on a Cu(111) surface partly covered with NaCl, two different rod structures of PTCDA were found on the copper surface, which are in contrast to previously published data for PTCDA on Cu(111) showing a herringbone-like arrangement. These findings can be explained by the formation of a Na(x)-PTCDA complex. On NaCl covered areas, single PTCDA molecules adsorb at vacancies of [010] and [001] oriented steps of the NaCl(100) islands. In this case, the electrostatic forces between the polar step edges and the PTCDA molecules are dominant. The terraces of the alkali halide surface are free of PTCDA molecules.

The binary molecular system of C60 and copper phthalocyanine(CuPc) molecules has been investigated by scanning tunneling microscopy (STM) at room temperature and at 50 K. As substrate Au(111) was chosen. When C60 and CuPc molecules are sequentially deposited, it is found that well‐ordered domains of both molecules may coexist simultaneously. Hence hexagonal ordering of C60 and quadratic ordering of CuPc is observed side by side but no ordered mixed layer of both molecules or heteroepitaxy from one molecule on the other is found. Instead the boundaries of the CuPc domains are often decorated by C60 molecules and for a particular choice of parameters, with regard to the film preparation, individual CuPc molecules may adsorb on top of a C60 layer. The interaction with the underlying C60 layer permits the molecules to perform a localized, hindered rotation. At room temperature the hopping frequency is so high that only the time average of the rotation is seen by STM while at 50 K the rotation is frozen and the CuPc molecule is trapped in one definite position.