Spectroscopic characterization of functionalized graphene nanoribbon heterostructures

石墨烯纳米带是最新的一维（1D） sp2-碳同素异形体，它结合了纳米管和石墨烯的最佳特性，即多种可能的结构和均匀晶圆涂层的可能性。石墨烯和石墨烯纳米带之间的一个关键区别是后者具有带隙。此外，可以通过控制其宽度和边缘结构来定制gnr的电子和光学特性。gnr可以通过自下而上的方法在催化活性金属表面上以原子精度制造，其前体分子在其上反应形成所需的结构。前体分子的多样性保证了具有不同物理性质的gnr可以大面积合成。此外，通过使用邻近表面，带状可以对齐。在这个项目中，我们将合成、功能化和光谱表征新型石墨烯纳米带及其异质结构，并评估其在设备中的潜在适用性。我们采用表面聚合的方法合成了GNRs，并对合成参数进行了优化。石墨烯纳米带将进一步功能化，例如在其上蒸发金属和土碱金属，以实现高电子掺杂。在合成过程中，通过不同前驱体的共蒸发或不同宽度、不同掺杂方式的堆叠，可以制备出不同结构的gnr。制备的样品将使用特高压光谱、光电子光谱、荧光和拉曼光谱进行表征。利用这些方法，我们将确定石墨烯纳米带的基本性质，如有效质量、激子跃迁能和吸收光谱。我们还将应用等离子体增强来增强gnr的光-物质相互作用。这里的一个关键目标是减少样品的探测面积，以便可以对单个纳米带进行光学研究。最后，我们将探讨gnr在气体传感等设备和应用中的应用。

Graphene nanoribbons are the latest one-dimensional (1D) sp2-carbon allotrope and combine the best attributes from the nanotube and the graphene worlds, i.e. a variety in possible structures with the possibility of a uniform wafer coating. A key difference between graphene and graphene nanoribbons is that the latter possess a bandgap. Furthermore, the electronic and optical properties of GNRs can be tailored by controlling their width and edge structure. GNRs can be fabricated with atomic precision by a bottom-up approach on a catalytically active metal surface on which precursor molecules react to form the desired structure. The large variety in precursor molecules ensures that GNRs with different physical properties can besynthesized over large areas. Additionally, by using vicinal surfaces the ribbons can be aligned. Within this project we will synthesize, functionalize, and spectroscopically characterize novel graphene nanoribbons and heterostructures made thereof and evaluate their potential applicability in devices. For the synthesis of GNRs we employ on-surface polymerization and will optimize the synthesis parameters. Graphene nanoribbons will be further functionalized by for example evaporation of metals and earth alkali metals on them to achieve high electron doping. Heterostructures of GNRs will be prepared by co-evaporation of different precursors during the synthesis step or by stacking GNRs with different width or doping. The fabricated samples will be characterized using UHV optical spectroscopy, photoelectron spectroscopy, and fluorescence and Raman spectroscopy. Using these methods we will determine fundamental properties of graphene nanoribbons such as effective masses, exciton transition energies, and absorption spectra. We will additionally apply plasmonic enhancement to enhance the light-matter interaction of GNRs. Here a key goal is to reduce the probed area of the sample so that individual nanoribbons may be studied optically. Finally, we will explore the use of GNRs in devices and applications such as gas sensing.