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

今天，纳米级的器件推动着密集的研究，并将在未来对纳米电子领域以及生物化学和医学领域产生更大的影响。针尖增强拉曼散射(TERS)是深入了解这类器件功能的理想方法，因为它结合了纳米级空间分辨率的微观和光谱信息。这个项目将充分发挥TERS的潜力，来表征和研究纳米级设备的结构。最适合本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显示出很高的应用潜力。另一方面，人们对碳纳米管上的拉曼光谱有了很好的了解，并展示了碳纳米管上的TERS。然而，关于碳纳米管和其他嫁接到碳纳米管上的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，将高分辨率透射电子显微镜与拉曼光谱和同一碳纳米管上的TERS相关联，并使用完整的光谱信息。能量过滤电子能量损失谱提供元素选择性，并将用于确定TERS的空间分辨率和化学选择性。拉曼光谱中的共振效应使人们能够洞察材料的电子态。因此，研究共振效应对功能化碳纳米管TERS谱的影响将有助于理解官能化对碳纳米管电子性质的影响，例如掺杂或产生缺陷。该项目的最终目标是将结果结合起来，选择那些在功能化碳纳米管上具有最有希望和最有趣的运输设备特性的位置。

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.