Real-time view of single molecule motion with aberration corrected LEEM

原子和分子在原子控制表面上的自组装为纳米结构的制造提供了良好的可能性。扩散，即原子或分子的热激活运动，起着重要的作用。过去，人们对原子体系的扩散过程进行了详细的研究，现在人们对原子体系的扩散过程有了很好的了解。对于有机分子，扩散和自组装更为复杂。由于某些有机分子结构复杂，必须考虑其他影响，例如分子内部的电荷转移或空间结合能的不同。扫描隧道显微镜（STM）显示，多苯基-二羰基分子在金属表面形成不同的网络。在交点上，分子的取向可以发生很大的变化。由于stm研究是在低温下进行的，在自组装过程完成后，这种技术无法监测自组装过程中分子运动的动力学。低能电子显微镜（LEEM）像差校正技术的最新进展，将分辨率提高到1.4 nm，这是polyphenyl - diccarbonnitril分子长度的数量级。单分子，例如长度为3nm的六苯基二碳腈，特别是它们的取向，现在可以在室温下用LEEM监测。本文将实时研究双羰基二腈在银和铜表面自组装过程中的分子运动，重点研究分子取向及其对自组装和扩散的影响。

Self-Assembly of atoms and molecules on atomically-controlled surfaces provides a good possibility to fabricate nanostructures. The diffusion, i.e. the thermal activated motion of the atoms or molecules, plays an important role. In the past, the diffusion processes of atomic systems were studied in detail and now are well understood.For organic molecules, diffusion and self-assembly are more complicated. Due to the complex structure of some organic molecules, additional influences, e.g. charge transfer inside the molecules or spatial different binding energies, have to be considered. Scanning Tunneling Microscopy (STM) shows that Polyphenyl-Dicarbonitril molecules form different networks on metallic surfaces. In the point of intersection, the molecule orientation can vary significantly. Since the STM-studies are performed at low temperatures, after the self-assembly process is completed, the dynamics of the molecule motion during self-assembly cannot be monitored with this technique.The recent progress in aberration correction for Low Energy Electron Microscopy (LEEM), improves the resolution down to 1.4 nm, which is in the order of magnitude of the length of Polyphenyl-Dicarbonitril molecules. Single molecules, e.g. Sexiphenyl-Dicarbonitril with a length of 3 nm, and especially their orientation can now be monitored in LEEM at room temperature. Here the molecule motion during self-assembly of Sexiphenyl-Dicarbonitril on silver and copper surfaces shall be studied in real-time with emphasis on the molecule orientation and its influence to self-assembly and diffusion.