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Carbyne, a linear chain of carbon atoms, is the truly one-dimensional allotrope of carbon and the strongest known Raman scatterer. Here, we use tip-enhanced Raman scattering (TERS) to further enhance the Raman response of a single carbyne chain confined inside a double-walled carbon nanotube. We observe an increase of the anti-Stokes scattering by a factor of 3290 and a 22-fold enhancement of the anti-Stokes/Stokes ratio relative to far-field measurements. The power dependence of the anti-Stokes/Stokes ratio under TERS conditions is indicative of coherent Stokes–anti-Stokes scattering mediated by an excited phonon. The role of resonance effects and laser-induced heating are discussed and potential opportunities are outlined., Nano Letters, 22 (8), ISSN:1530-6984, ISSN:1530-6992

Long linear chains of carbon encapsulated in carbon nanotubes represent the finite realization of carbyne, the truly one-dimensional carbon allotrope. Driven by advances in the synthesis of such structures, carbyne has attracted significant interest in recent years, with numerous experimental studies exploring its remarkable properties. As for other carbon nanomaterials, Raman spectroscopy has played an important role in the characterization of carbyne. In particular, tip-enhanced Raman scattering (TERS) has enabled imaging and spectroscopy down to the single-chain level. In this article, we provide a general introduction to carbyne and discuss the principles and experimental implementation of TERS as a key technology for the investigation of this material system. Within this context, the development of optical nanoantennas as TERS probes is addressed. We then summarize the latest progress in the Raman spectroscopic characterization of confined carbyne, with a focus on the findings assisted by TERS. Finally, we discuss open questions in the field and outline how TERS can contribute to solving them in future studies., The Journal of Chemical Physics, 156 (4), ISSN:0021-9606, ISSN:1089-7690