The implementation of force detection in experiments on electron transport through single molecules

通过扫描隧道显微镜（STM），它是可能的调查电子传输通过吸附物和吸附物结构在各种各样的方面，同时有确切的知识和控制的原子结构，包括耦合到铅。因此，STM在分子电子学领域得到了非常成功的应用。然而，STM研究仅限于导电衬底，并且实验数据由样品的几何结构和电子结构以复杂且通常模糊的方式确定。为了克服这两个局限性，预计将实验实施力检测作为分子电子学中的附加措施，即通过单个分子的电子传输测量。为此，在持续供资期间建造了一台尖端配备力检测器的扫描隧道显微镜。计划测量接触形成后作用于单分子尖端的力，以提供可用于建模和理解接触形成的更完整的实验数据集。其次，我们想利用力检测来明确区分成像中以及任何电子传输测量中的电流信号中的电子效应和几何效应。第三，将探讨通过静电力检测来量化分子和分子结构中的电荷再分布的可能性。最后，力检测将允许在样品的完全绝缘区域上研究导电分子结构。总之，这个项目将建立通过分子和工程分子结构的电子传输实验中的力的检测，从而提供一个更好的控制原子尺度精度的分子电子学的几何形状。

By means of scanning tunneling microscopy (STM) it is possible to investigate electron transport through adsorbates and adsorbate structures in a large variety of aspects, while having exact knowledge and control of the atomistic structure including the coupling to the leads. Therefore, STM has been very successfully applied in the field of molecular electronics. However, STM investigations are limited to conducting substrates and the experimental data is determined by both the geometry and the electronic structure of the sample in a complex and often ambiguous manner. To overcome these two limitations, it is projected to experimentally implement force detection as an additional measure in molecular electronics, that is, in electron transport measurements through a single molecule. To this end, a scanning tunneling microscope equipped with a force detector at the tip was built in the ongoing funding period. It is planned to measure the forces that act on the tip upon contact formation to a single molecule, to provide a more complete set of experimental data that can be used to model and understand the contact formation. Second, we would like to exploit the force detection to unambiguously discriminate between electronic and geometric effects in the current signal in imaging as well as in any electron-transport measurement. Third, the possibilities in quantifying charge redistribution in molecules and molecular structures by electrostatic force detection will be explored. Finally, force detection will allow the investigation of conducting molecular structures on completely insulating areas of a sample. Altogether this project shall establish the detection of forces in experiments on electron transport through molecules and engineered molecular structures and thereby provide a better control of the geometry in molecular electronics with atomic-scale precision.