Long linear carbon chains (LLCCs) encapsulated inside double-walled carbon nanotubes (DWCNTs) are regarded as a promising realization of carbyne, the truly one-dimensional allotrope of carbon. While the electronic and vibronic properties of the encapsulated LLCC are expected to be influenced by its nanotube host, this dependence has not been investigated experimentally so far. Here we bridge this gap by studying individual LLCCs encapsulated in DWCNTs with tip-enhanced Raman scattering (TERS). We reveal that the nanotube host, characterized by its chirality, determines the vibronic and electronic properties of the encapsulated LLCC. By choice of chirality, the fundamental Raman mode (C-mode) of the chain is tunable by ∼95 cm^–1 and its band gap by ∼0.6 eV, suggesting this one-dimensional hybrid system to be a promising building block for nanoscale optoelectronics. No length dependence of the chain’s C-mode frequency is evident, making LLCCs a close to perfect representation of carbyne.

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碳纳米管手性决定了封装的线性碳链的性质

封装在双壁碳纳米管（DWCNT）内的长线性碳链（LLCC）被认为是真正有前途的碳一维同素异形体。虽然预期封装的LLCC的电子和振动特性会受到其纳米管主体的影响，但到目前为止，尚未通过实验研究这种依赖性。在这里，我们通过研究用尖端增强拉曼散射（TERS）封装在DWCNT中的单个LLCC来弥合这一差距。我们发现，以其手性为特征的纳米管主体决定了封装的LLCC的振动和电子特性。通过选择手性，链的基本拉曼模式（C模式）可调节约95 cm ^–1且其带隙约为0.6 eV，这表明该一维混合系统是纳米光电的有前途的构建基块。没有明显的长度依赖于链的C模频率，这使得LLCCs几乎可以完美地代表出碳炔。