Fabrication of well-defined nanoscale electrodes for stable and reproducible contacts to small molecular ensembles

纳米级分子结的制备通常会遇到金属分子接触定义不明确的问题。这导致结果在很大范围内变化，即使名义上系统中的外部参数没有改变。基于这样的实验，只能得出统计结论。为了表征这种连接中的分子性质，金属和分子之间的接触在原子尺度上是可重现的，这是必不可少的。当然，这一要求不能通过简单地优化两个部分(分子或金属接触)中的一个来满足。触点的两个组成部分都必须作为一个单一的复合系统进行优化。最近有研究表明，由荫罩蒸发制成的结显示出分子特有的行为。与其他现有技术的重要区别是这些结果的高度重复性。因此，我们计划系统地研究不同的分子端基/金属组合对通过分子结的传导机制的影响。

The fabrication of nanoscale molecular junctions usually suffers from poorly defined metalmolecule contacts. This leads to results which vary over broad ranges even if nominally no external parameter in the system has been changed. Based on such experiments only statistical conclusions can be drawn. For the characterization of molecular properties in such junctions it is indispensable that the contact between metal and the molecule is reproducible at the atomic scale. Of course this requirement cannot be fulfilled by simply optimizing one of the two parts (the molecule or the metallic contact). Both constituents of the contact have to be optimized as one single composite system. It could recently be shown that junctions fabricated by shadow-mask evaporation show molecule specific behavior. The important difference to other existing techniques is the high reproducibility of these results. We therefore plan to investigate the influence of different molecular endgroup/metal combinations on the conduction mechanism through the molecular junction systematically.