title: Fabrication and optical probing of highly extended, ultrathin graphene nanoribbons in carbon nanotubes.
abstract: Nanotemplated growth of graphene nanoribbons (GNRs) inside carbon nanotubes is a promising mean to fabricate ultrathin ribbons with desired side edge configuration. We report the optical properties of the GNRs formed in single-wall carbon nanotubes. When coronene is used as the precursor, extended GNRs are grown via a high-temperature annealing at 700 °C. Their optical responses are probed through the diazonium-based side-wall functionalization, which effectively suppresses the excitonic absorption peaks of the nanotubes without damaging the inner GNRs. Differential absorption spectra clearly show two distinct peaks around 1.5 and 3.4 eV. These peaks are assigned to the optical transitions between the van Hove singularities in the density of state of the GNRs in qualitative agreement with the first-principles calculations. Resonance Raman spectra and transmission electron microscope observations also support the formation of long GNRs.
authors: †Department of Chemistry, Nagoya University, Nagoya 464-8602, Japan.
authors: Hong En
authors: HE
authors: Lim
authors: ‡Department of Physics, Tokyo Metropolitan University, Hachioji 192-0397, Japan.|§JST, PRESTO, Kawaguchi 332-0012, Japan.
authors: Yasumitsu
authors: Y
authors: Miyata
authors: †Department of Chemistry, Nagoya University, Nagoya 464-8602, Japan.
authors: Miho
authors: M
authors: Fujihara
authors: ⊥Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba 305-8571, Japan.
authors: Susumu
authors: S
authors: Okada
authors: ∥Nanotube Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8565, Japan.
authors: Zheng
authors: Z
authors: Liu
authors: †Department of Chemistry, Nagoya University, Nagoya 464-8602, Japan.
authors: Arifin
authors: ∥Nanotube Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8565, Japan.
authors: Kayoko
authors: K
authors: Sato
authors: †Department of Chemistry, Nagoya University, Nagoya 464-8602, Japan.
authors: Haruka
authors: H
authors: Omachi
authors: †Department of Chemistry, Nagoya University, Nagoya 464-8602, Japan.
authors: Ryo
authors: R
authors: Kitaura
authors: †Department of Chemistry, Nagoya University, Nagoya 464-8602, Japan.|#WPI-Institute of Transformative Bio-Molecules (ITbM), Nagoya University, Nagoya 464-8602, Japan.
authors: Stephan
authors: S
authors: Irle
authors: ∥Nanotube Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8565, Japan.
authors: Kazu
authors: K
authors: Suenaga
authors: †Department of Chemistry, Nagoya University, Nagoya 464-8602, Japan.|○Institute for Advanced Research, Nagoya University, Nagoya 464-8602, Japan.
authors: Hisanori
authors: H
authors: Shinohara
keywords: functionalization; graphene nanoribbons; optical absorption; single-wall carbon nanotubes