Graphene nanoribbons with sub-nanometer widths are extremely interesting for nanoscale electronics and devices as they combine the unusual transport properties of graphene with the opening of a band gap due to quantum confinement in the lateral dimension. Strong research efforts are presently paid to grow such nanoribbons. Here we show the synthesis of 6- and 7-armchair graphene nanoribbons, with widths of 0.61 and 0.74 nm, and excitonic gaps of 1.83 and 2.18 eV, by high-temperature vacuum annealing of ferrocene molecules inside single-walled carbon nanotubes. The encapsulation of the so-obtained graphene nanoribbons is proved by atomic resolution electron microscopy, while their assignment is provided by a combination of an extensive wavelength-dependent Raman scattering characterization and quantum-chemical calculations. These findings enable a facile and scalable approach leading to the controlled growth and detailed analysis of well-defined sub-nanometer graphene nanoribbons.
@article{arxiv.2006.13444,
title = {Well-defined sub-nanometer graphene ribbons synthesized inside carbon nanotubes},
author = {Hans Kuzmany and Lei Shi and Miles Martinati and Sofie Cambré and Wim Wenseleers and Jenő Kürti and János Koltai and Gergő Kukucska and Kecheng Cao and Ute Kaiser and Takeshi Saito and Thomas Pichler},
journal= {arXiv preprint arXiv:2006.13444},
year = {2020}
}