Unraveling the governing properties of confined carbyne through the interaction with its carbon nanotube host

Linear carbon chains (LCCs), synthesized using carbon nanotubes (CNTs) as templates, exhibit intriguing properties that are not dependent on their length. Consequently, LCCs can also be identified as carbyne. Since such carbyne only exists confined to CNT, it is commonly called confined carbyne (CC). In this study, we investigate the interaction between CC and double-walled CNTs (DWCNTs) through resonance Raman spectroscopy. The optical band gaps and Raman frequencies of inner (6,4) and (6,5) CNTs are influenced both externally by the outer CNTs and internally by the encapsulated CCs. Remarkably, our findings demonstrate that the properties of CC are determined by the interaction between the encapsulated CC and the CNT. As a result, the optical band gap of the encapsulated CC is solely dictated by the hosting CNT, rendering it identical to the host's gap. Therefore, we propose a novel approach to tailor the properties of CC by selecting the appropriate chirality of the CNT. These findings pave the way for future applications of CC with tailored properties, offering promising application opportunities of this material as semiconductor.