发表机构
Karlsruhe Institute of Technology; Humboldt-Universität zu Berlin; Center for the Science of Materials Berlin, Humboldt-Universität zu Berlin; Politecnico di Milano; Huzhou Normal University（卡尔斯鲁厄理工学院; 柏林洪堡大学; 柏林材料科学中心; 米兰理工大学; 湖州师范学院）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究在超薄氮化硼纳米管中热转化聚炔，实现近理想卡宾链，通过拉曼光谱验证其振动频率分布窄、非谐性符合普适定律，为测量卡宾固有性质提供途径。
AI 中文摘要
卡宾是碳的sp杂化一维同素异形体，被预测为已知最坚硬的材料，其电子和光学性质由单一结构参数——键长交替度决定。然而，其固有性质从未被测量过：通过分子化学合成的链带有端基和有限长度扰动，即使在可获得的最长分子中这些扰动依然存在；而在碳纳米管内生长的链与宿主强烈耦合，这使其振动频率以依赖直径的方式重正化高达110 cm$^{-1}$。在此，我们展示了在超薄氮化硼纳米管（碳纳米管的结构类似物，但电绝缘）内封装并热转化氢封端的聚炔，可产生处于近理想状态的卡宾链，其中端基、有限长度和主客体扰动被降低为次要效应。对245个位置进行的统计拉曼光谱分析得出振动频率分布比碳纳米管窄一个数量级，非谐性与卡宾类材料的普适定律一致，键长交替度与自由链的相关计算匹配。尽管宿主透明，但未检测到光致发光，这符合未扰动卡宾链偶极禁戒发射的预期。氮化硼纳米管为实验获取近理想形式的卡宾提供了途径。
英文摘要
Carbyne, the sp-hybridized one-dimensional allotrope of carbon, is predicted to be the stiffest known material, with electronic and optical properties set by a single structural parameter, the bond length alternation. However, its intrinsic properties have never been measured: chains synthesized through molecular chemistry carry endgroup and finite-length perturbations that persist even in the longest molecules available, while chains grown inside carbon nanotubes strongly couple to the host, which renormalizes their vibrational frequency by up to 110 cm$^{-1}$ in a diameter-dependent manner. Here, we show that encapsulating and thermally converting hydrogen-capped polyynes inside ultrathin boron nitride nanotubes, structural analogues of carbon nanotubes but electrically insulating, yields carbyne chains in a near-ideal regime, where endgroup, finite length, and host-guest perturbations are reduced to secondary effects. Statistical Raman spectroscopy across 245 locations returns a vibrational frequency distribution an order of magnitude narrower than in carbon nanotubes, an anharmonicity consistent with the universal law for carbyne-like materials, and a bond length alternation matching correlated calculations for the free chain. No photoluminescence is detected, despite the transparent host, as expected for the dipole-forbidden emission of an unperturbed carbyne chain. Boron nitride nanotubes give experimental access to carbyne in its near-ideal form.
Comments4 figures, 14 pages
