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

这个项目的主要目标将是研究单分子的电子和电导性质的演变，研究作为(I)与载体的耦合强度和(Ii)分子间相互作用的函数。为此，简单的烷烃和共轭分子被沉积在对分子施加不同结合强度的表面上，例如惰性氧化物、半导体和金属表面。用低温扫描隧道显微镜的电导光谱对分子态密度(DOS)进行了研究。这些实验将提供关于几乎解耦的分子的能级以及强结合的分子-底物单元的信息，从而反映键形成对分子电子系统的影响。这些结果可作为各系统理论模型的输入参数，由施沃朋克方案的参与组执行。在第二步中，通过用STM尖端操纵单个分子来形成定义明确的分子组件。这些实验侧重于分子间相互作用对DOS的影响以及形成耦合分子体系的可能性。电导测量与STM的单分子振动和光学光谱相补充，生成关于分子中结合强度和能级位置的额外数据。该项目旨在提供信息，如何通过对分子载体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.