Borin Barin Gabriela, Di Giovannantonio Marco, Lohr Thorsten G, Mishra Shantanu, Kinikar Amogh, Perrin Mickael L, Overbeck Jan, Calame Michel, Feng Xinliang, Fasel Roman, Ruffieux Pascal
Nanotech@Surfaces Laboratory, Empa, Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland.
Center for Advancing Electronics Dresden, Department of Chemistry and Food Chemistry, TU Dresden, Dresden 01062, Germany.
Nanoscale. 2023 Oct 26;15(41):16766-16774. doi: 10.1039/d3nr03736c.
Graphene nanoribbons (GNRs) exhibit a broad range of physicochemical properties that critically depend on their width and edge topology. GNRs with armchair edges (AGNRs) are usually more stable than their counterparts with zigzag edges (ZGNRs) where the low-energy spin-polarized edge states render the ribbons prone to being altered by undesired chemical reactions. On the other hand, such edge-localized states make ZGNRs highly appealing for applications in spintronic and quantum technologies. For GNRs fabricated on-surface synthesis under ultrahigh vacuum conditions on metal substrates, the expected reactivity of zigzag edges is a serious concern in view of substrate transfer and device integration under ambient conditions, but corresponding investigations are scarce. Using 10-bromo-9,9':10',9''-teranthracene as a precursor, we have thus synthesized hexanthene (HA) and teranthene (TA) as model compounds for ultrashort GNRs with mixed armchair and zigzag edges, characterized their chemical and electronic structure by means of scanning probe methods, and studied their chemical reactivity upon air exposure by Raman spectroscopy. We present a detailed identification of molecular orbitals and vibrational modes, assign their origin to armchair or zigzag edges, and discuss the chemical reactivity of these edges based on characteristic Raman spectral features.
石墨烯纳米带（GNRs）展现出广泛的物理化学性质，这些性质严重依赖于它们的宽度和边缘拓扑结构。具有扶手椅边缘的GNRs（AGNRs）通常比具有锯齿边缘的GNRs（ZGNRs）更稳定，在ZGNRs中，低能量自旋极化边缘态使纳米带易于被不期望的化学反应改变。另一方面，这种边缘局域态使得ZGNRs在自旋电子学和量子技术应用中极具吸引力。对于在超高真空条件下在金属衬底上通过表面合成制备的GNRs，考虑到在环境条件下的衬底转移和器件集成，锯齿边缘预期的反应活性是一个严重问题，但相应的研究很少。因此，我们使用10-溴-9,9':10',9''-三联蒽作为前驱体，合成了己并苯（HA）和三联并苯（TA）作为具有混合扶手椅和锯齿边缘的超短GNRs的模型化合物，通过扫描探针方法表征了它们的化学和电子结构，并通过拉曼光谱研究了它们在空气暴露下的化学反应活性。我们详细识别了分子轨道和振动模式，将它们的起源归因于扶手椅或锯齿边缘，并基于特征拉曼光谱特征讨论了这些边缘的化学反应活性。
