Synthesis of graphene nanoribbons on a kinked au surface: Revealing the frontier valence band at the brillouin zone center

Graphene nanoribbons (GNRs) can be synthesized with atomic precision through on-surface chemistry of self-assembled organic precursors on metal surfaces. Here, we examine the growth of seven-armchair GNRs (7-AGNRs) on the Au(16 14 15) vicinal surface, namely, a surface vicinal to Au(111) that features kinked steps. During the thermal activation of the polymerization and cyclodehydrogenation processes that produce the GNRs, the kinked substrate undergoes a strong step-edge reshaping, accompanied by a massive missing-row reconstruction within (111) terraces that aligns GNRs preferentially along two equivalent [11¯ 0] directions. Using angle-resolved photoemission, we are able to detect the occupied frontier band of the 7-AGNR at the center of the first Brillouin zone, as predicted by theoretical calculations. This allows to unambiguously determine the relevant 7-AGNR band properties, namely, energy and effective mass.The authors acknowledge financial support from the Spanish Ministry of Science and Innovation (MAT2016-78293-C6), from the Basque Government (IT-1255-19), from the Spanish National Research Council (CSIC, 2019AEP062), from the European Regional Development Fund (ERDF) under the program Interreg V-A España-Francia-Andorra (contract no. EFA 194/16 TNSI) and from the European Research Council (grant agreement no. 635919)