Differential conductance measurements of single test molecules on various supports by lowtemperature STM to quantify the influence of molecule-support and inter-molecular interactions on a molecular electronic system

该项目的主要目标是研究单分子的电子和电导特性的演变，研究其与(i)与载体的耦合强度和（ii）分子间相互作用的函数关系。为此，简单烷烃和共轭分子沉积在对分子具有不同结合强度的表面上，如惰性氧化物、半导体和金属表面。用低温STM电导光谱法探测了分子态密度（DOS）。实验将提供近解耦分子和强结合分子-底物单元的能级信息，从而反映成键对分子电子系统的影响。这些结果可以作为各自系统理论建模的输入参数，由该schwerpunktprogram的参与小组执行。在第二步中，通过使用STM尖端操纵单个分子来形成定义良好的分子组装。这些实验的重点是分子间相互作用对DOS的影响以及形成耦合分子体系的可能性。利用STM对单分子进行振动光谱和光学光谱分析，补充电导测量，生成关于分子结合强度和水平位置的额外数据。该项目旨在提供信息，如何通过分子支持和分子间相互作用的系统修改来控制分子连接的传输特性。

The major objective of this project will be a study of the evolution of electronic and conductance properties of single molecules, investigated as a function of (i) coupling strength to a support and (ii) inter-molecular interactions. For this purpose, simple alkanes and pconjugated molecules are deposited on surfaces exerting different binding strengths towards molecules, such as inert oxide, semiconductor and metal surfaces. The molecular density of states (DOS) is probed by conductance spectroscopy with a low-temperature STM. The experiments will provide information on the energy levels of nearly decoupled molecules as well as strongly bound molecule-substrate units, thus reflecting the influence of bond formation on the molecular electronic system. The results can serve as input parameters for a theoretical modelling of the respective systems, performed by participating groups of this Schwerpunktprogramm. In a second step, well-defined molecular assemblies are formed by manipulation of individual molecules with the STM tip. These experiments focus on the influence of inter-molecular interactions on the DOS and on the possibility to form coupled molecular systems. Conductance measurements are complemented by vibrational and optical spectroscopy of single molecules with the STM, generating additional data on binding strength and level positions in the molecules. The project aims to provide information, how the transport properties of a molecular junction can be controlled by a systematic modifications of molecule-support and inter-molecular interactions.