发表机构
Laboratory of NanoEngineering, College of Technology, University of Brasília; Graduate Program in Physics, Institute of Physics, University of Brasília; Center for Agri-Food Science and Technology, Federal University of Campina Grande; Institute of Physics, Federal University of Rio Grande do Norte; Department of Applied Physics, Gleb Wataghin Institute of Physics, University of Campinas; Department of Electrical Engineering, College of Technology, University of Brasília（巴西利亚大学技术学院纳米工程实验室; 巴西利亚大学物理研究所物理研究生项目; 坎皮纳格兰德联邦大学农业食品科学与技术中心; 北里奥格兰德联邦大学物理研究所; 坎皮纳斯大学格列布·瓦塔金物理研究所应用物理系; 巴西利亚大学技术学院电气工程系）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过原子级表征揭示了穿孔和氮掺杂在扶手椅型石墨烯纳米带中的不同作用：穿孔主导力学热学性质，氮掺杂控制电子光学性质，并发现其声子平均自由程与合成长度匹配。
AI 中文摘要
通过表面合成获得的石墨烯纳米带（GNR）将宽度可控的带隙与原子级精度相结合，使得对其边缘和内部进行化学修饰成为设计电子和光学行为的实用途径。含吩嗪前体的乌尔曼偶联反应生成一条九原子宽的扶手椅型纳米带，该纳米带周期性穿孔，且每个孔边缘带有两个二配位氮原子。在此，我们对该纳米带以及原始未掺杂多孔纳米带在器件运行相关性质方面进行了表征，厘清了成孔和氮掺杂各自的作用。穿孔主要决定力学和热学响应，而氮取代主要控制电子和光学性质。穿孔移除了承载前沿态的原子行，将带隙打开至隧穿光谱测量到的范围，同时显著降低了刚度和热导率。取代几乎不改变力学响应，并通过声子谱重新加权贡献了二次电导率降低。其主要效应是电子方面的：它选择性地收窄导带，将最低激子束缚能提高414 meV，并将吸收边移至红光区。我们获得的声子有效平均自由程为9.9 nm，与当前合成方法限制这些纳米带的长度相匹配，使所报道的样品处于弹道-扩散交叉区域。在Au(111)、Ag(111)和Cu(111)上的吸附在能量上几乎无法区分，且保持范德华特性，这解释了实验观察到的基底耐受性。最后，石墨型而非吡嗪型氮会使纳米带呈金属性，除非两个原子占据孔边缘位点，此时产生铁磁性半导体态，每个晶胞的磁矩为2 μ_B。
英文摘要
Graphene nanoribbons (GNRs) obtained by on-surface synthesis combine a width-controlled band gap with atomic precision, making chemical decoration of their edges and interiors a practical route to designed electronic and optical behavior. Ullmann coupling of a phenazine-bearing precursor yields a nine-atom-wide armchair ribbon that is periodically perforated and carries two two-coordinated nitrogen atoms at every pore rim. Here we characterize this ribbon across the properties relevant to device operation, alongside the pristine and undoped porous ribbon, disentangling the roles of pore formation and nitrogen incorporation. Perforation primarily governs mechanical and thermal response, whereas nitrogen substitution predominantly controls electronic and optical properties. Perforation removes the atomic row carrying frontier states, opening the gap into the range measured by tunneling spectroscopy while substantially reducing stiffness and thermal conductivity. Substitution leaves the mechanical response essentially unchanged and contributes a secondary conductivity reduction through phonon spectrum reweighting. Its primary effect is electronic: it selectively narrows the conduction band, binds the lowest exciton by 414 meV, and displaces the absorption edge into the red. The effective phonon mean free path we obtain, 9.9 nm, matches the length to which the synthesis presently limits these ribbons, placing reported samples at the ballistic-to-diffusive crossover. Adsorption on Au(111), Ag(111), and Cu(111) is energetically nearly indistinguishable and remains van der Waals in character, accounting for the substrate tolerance observed experimentally. Finally, graphitic rather than pyrazinic nitrogen would make the ribbon metallic, except when two atoms occupy pore-rim sites, yielding a ferromagnetic semiconducting state having a magnetic moment of 2 mu_B per unit cell.
Comments15 pages and 8 figures
