该课题组用原子尺度的空间分辨率探测了金属表面合成的GNRs的激子发射。采用扫描隧道显微镜(STM)将GNRs转移到部分绝缘表面，以防止带的荧光猝灭。STM诱导的荧光光谱揭示了来自局域暗激子的发射，这些暗激子与GNRs的拓扑端态相关联。此外，他们还观察到了局限于有限空间的纵向声学模引起的低频电子振动发射梳状结构。这项研究为探究石墨烯纳米结构中激子、振子和拓扑之间的相互作用提供了新的途径。
据悉，由于由金属衬底上生长的纳米带会出现荧光猝灭效应，导致原子级精度石墨烯纳米带（GNRs）的固有光电特性仍然鲜为人知。
附：英文原文
Title: Topologically localized excitons in single graphene nanoribbons
Author: Song Jiang, Tomá Neuman, Alex Boeglin, Fabrice Scheurer, Guillaume Schull
Issue&Volume: 2023-03-10
Abstract: Intrinsic optoelectronic properties of atomically precise graphene nanoribbons (GNRs) remain largely unexplored because of luminescence quenching effects that are due to the metallic substrate on which the ribbons are grown. We probed excitonic emission from GNRs synthesized on a metal surface with atomic-scale spatial resolution. A scanning tunneling microscope (STM)–based method to transfer the GNRs to a partially insulating surface was used to prevent luminescence quenching of the ribbons. STM-induced fluorescence spectra reveal emission from localized dark excitons that are associated with the topological end states of the GNRs. A low-frequency vibronic emission comb is observed and attributed to longitudinal acoustic modes that are confined to a finite box. Our study provides a path to investigate the interplay between excitons, vibrons, and topology in graphene nanostructures.
DOI: abq6948
Source: https://www.science.org/doi/10.1126/science.abq6948