Tip-enhanced Raman scattering unraveling molecular interactions in individual carbon nanotube systems

在纳米尺度上的器件推动了今天的深入研究，并将在未来对纳米电子学领域以及生物化学和医学领域产生更大的影响。尖端增强拉曼散射（TERS）是深入了解此类器件功能的理想方法，因为它结合了纳米尺度空间分辨率下的微观和光谱信息。该项目将充分发挥纳米尺度器件在表征和研究结构方面的潜力。最适合这项研究的模型体系是功能化碳纳米管（CNTs）。一方面，它们在纳米传感器或单分子探测器方面具有很高的应用潜力。另一方面，人们对碳纳米管上的拉曼光谱已经有了很好的了解，并且已经证实了碳纳米管上的TERS。然而，关于碳纳米管与接枝到碳纳米管上的其他分子之间相互作用的知识仍然有限。我们将研究这种相互作用，特别是与磁性分子的相互作用，将高分辨率透射电子显微镜与拉曼光谱和相同碳纳米管上的TERS相关联，并使用全光谱信息。能量过滤电子能量损失能谱提供了元素选择性，并将用于确定空间分辨率以及化学选择性的TERS。拉曼光谱中的共振效应使我们能够深入了解材料的电子态。因此，研究共振效应对功能化碳纳米管的TERS谱的影响将有助于理解功能化对碳纳米管电子性质的影响，例如，通过掺杂或产生缺陷。该项目的最终目标是将这些结果结合起来，选择那些功能化碳纳米管上最有希望和最有趣的运输设备性质的位点。

Devices on the nanometer scale drive intensive research today and will gain even more influence in the future for both the field of nanoelectronics and the field of biochemistry and medicine. Tip-enhanced Raman scattering (TERS) is an ideal method to understand the functionality of such devices in depth, since it combines microscopic with spectroscopic information at nanometer scale spatial resolution. This project is going to unfold the full potential of TERS to characterize and study the structure of nanoscale devices. The model systems most suitable for this investigation are functionalized carbon nanotubes (CNTs). On the one hand, they show a high potential for applications as nanosensors or single molecule detectors. On the other hand, Raman spectroscopy on CNTs is well understood, and TERS on CNTs has been demonstrated. However, knowledge about interactions between CNTs and other molecules grafted to them is still limited. We will study such interactions in particular with magnetic molecules, correlating high-resolution transmission electron microscopy with Raman spectroscopy and TERS on the same CNT and using the full spectral information. Energy filtered electron energy loss spectroscopy provides element selectivity and will be used to determine the spatial resolution as well as the chemical selectivity of TERS. The resonance effect in Raman spectroscopy gives insight into the electronic states of the material. Thus, studying the influence of the resonance effect on the TERS spectra of functionalized CNTs will lead to an understanding of the influence of the functionalization on the electronic properties of the CNT, e.g., by doping or creation of defects. The final goal of the project is then to combine the results to select those sites on functionalized CNTs with the most promising and the most interesting properties for transport devices.