We present laser-induced photothermal synthesis of atomically precise graphene nanoribbons (GNRs). The kinetics of photothermal bottom-up GNR growth are unravelled by in situ Raman spectroscopy carried out in ultrahigh vacuum. We photothermally drive the reaction steps by short periods of laser irradiation and subsequently analyze the Raman spectra of the reactants in the irradiated area. Growth kinetics of chevron GNRs (CGNRs) and seven atoms wide armchair GNRs (7-AGNRs) is investigated. The reaction rate constants for polymerization, cyclodehydrogenation, and interribbon fusion are experimentally determined. We find that the limiting rate constants for CGNR growth are several hundred times smaller than for 7-AGNR growth and that interribbon fusion is an important elementary reaction occurring during 7-AGNR growth. Our work highlights that photothermal synthesis and in situ Raman spectroscopy are a powerful tandem for the investigation of on-surface reactions.

中文翻译：

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光热自下而上的石墨烯纳米带生长动力学。

我们介绍了原子精确的石墨烯纳米带（GNRs）的激光诱导光热合成。光热自下而上的GNR生长的动力学通过原位揭示拉曼光谱在超高真空下进行。我们通过短时间的激光辐照来光热驱动反应步骤，然后分析辐照区域中反应物的拉曼光谱。研究了人字形GNR（CGNRs）和七个原子宽扶手椅GNR（7-AGNRs）的生长动力学。通过实验确定了聚合，环脱氢和链间熔融的反应速率常数。我们发现，CGNR生长的极限速率常数比7-AGNR生长的极限速率常数小数百倍，并且碳带间融合是7-AGNR生长期间发生的重要的基本反应。我们的工作强调，光热合成和原位拉曼光谱法是研究表面反应的有力工具。