Quantifying carbon-nanotube species with resonance Raman scattering

Jório, Ado; Santos, Adelina P.; Ribeiro, Henrique B.; Fantini, C.; Souza, Maria do Carmo; Vieira, Julia; Furtado, Clascídia Aparecida; Jiang, Jie; Saito, Riichiro; Balzano, Laura; Resasco, Daniel E.; Pimenta, M. A.

doi:10.1103/physrevb.72.075207

Cited by 160 publications

(192 citation statements)

References 16 publications

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“…18 In fact, our chiral angle distributions were even narrower than those of CoMoCat SWCNTs, 19,20 typically considered to have the narrowest distribution of all standard CVD methods. The observed fraction of semiconducting tubes in the 880 C sample was the expected 67%, whereas the 750 C one had a larger fraction of 80%.…”

Section: à3mentioning

confidence: 99%

Gas phase synthesis of non-bundled, small diameter single-walled carbon nanotubes with near-armchair chiralities

Mustonen

Laiho

Kaskela

et al. 2015

Applied Physics Letters

104

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We present a floating catalyst synthesis route for individual, i.e., non-bundled, small diameter single-walled carbon nanotubes (SWCNTs) with a narrow chiral angle distribution peaking at high chiralities near the armchair species. An ex situ spark discharge generator was used to form iron particles with geometric number mean diameters of 3–4 nm and fed into a laminar flow chemical vapour deposition reactor for the continuous synthesis of long and high-quality SWCNTs from ambient pressure carbon monoxide. The intensity ratio of G/D peaks in Raman spectra up to 48 and mean tube lengths up to 4 μm were observed. The chiral distributions, as directly determined by electron diffraction in the transmission electron microscope, clustered around the (n,m) indices (7,6), (8,6), (8,7), and (9,6), with up to 70% of tubes having chiral angles over 20°. The mean diameter of SWCNTs was reduced from 1.10 to 1.04 nm by decreasing the growth temperature from 880 to 750 °C, which simultaneously increased the fraction of semiconducting tubes from 67% to 80%. Limiting the nanotube gas phase number concentration to ∼105 cm−3 prevented nanotube bundle formation that is due to collisions induced by Brownian diffusion. Up to 80% of 500 as-deposited tubes observed by atomic force and transmission electron microscopy were individual. Transparent conducting films deposited from these SWCNTs exhibited record low sheet resistances of 63 Ω/□ at 90% transparency for 550 nm light.

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Section: à3mentioning

confidence: 99%

Gas phase synthesis of non-bundled, small diameter single-walled carbon nanotubes with near-armchair chiralities

Mustonen

Laiho

Kaskela

et al. 2015

Applied Physics Letters

104

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“…4a). The intensity of the tube peaks is only comparative, not absolute, as the efficiency of resonant energy transfer varies; 40 it is known, for example, that (6, 5) tubes dominate CoMoCAT samples, although they couple weakly to the red laser. In the spontaneous dissolution process, the intensity of the peaks correlating to the semiconducting SWNTs decrease strongly, disappearing almost entirely.…”

Section: Dmf Addition To the Nanotubide Salt -Swnt Separationmentioning

confidence: 99%

Scalable Method for the Reductive Dissolution, Purification, and Separation of Single-Walled Carbon Nanotubes

et al. 2011

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As synthesized, bulk singlewalled carbon nanotube (SWNT) samples are typically highly agglomerated and heterogeneous. However, their most promising applications require the isolation of individualized, purified nanotubes, often with specific optoelectronic characteristics. A wide range of dispersion and separation techniques have been developed, but the use of sonication or ultracentrifugation imposes severe limits on scalability and may introduce damage. Here, we demonstrate a new, intrinsically scalable method for SWNT dispersion and separation, using reductive treatment in sodium metal-ammonia solutions, optionally followed by selective dissolution in a polar aprotic organic solvent. In situ small-angle neutron scattering demonstrates the presence of dissolved, unbundled SWNTs in solution, at concentrations reaching at least 2 mg/mL; the ability to isolate individual nanotubes is confirmed by atomic force microscopy. Spectroscopy data suggest that the soluble fraction contains predominately large metallic nanotubes; a potential new mechanism for nanotube separation is proposed. In addition, the G/D ratios observed during the dissolution sequence, as a function of metal: carbon ratio, demonstrate a new purification method for removing carbonaceous impurities from pristine SWNTs, which avoids traditional, damaging, competitive oxidation reactions.

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“…For a more fair comparison between species within the same sample and between different samples, Raman data collected continuously over a broad excitation energy range ensures that each (n, m) species is sampled at its peak intensity producing a numerical intensity proportional to abundance. 127 However, this too can still be problematic as the peak "intensity" must be carefully interpreted, especially to account for the chiral-dependent optical transition line width, Γ el , as well as the RBM phonon line width, Γ ph , which can affect the observed peak height. The use of RBM peak area as opposed to RBM peak height as the quantity of comparison avoids the latter issue.…”

Section: Resonant Raman Scattering Spectroscopy Of Armchair-enricmentioning

confidence: 99%

“…By measuring a complete REP for a given species, the integrated RBM area for each (n, m) across the entire range of excitation can be calculated, which accounts for all the aforementioned issues. 127 Finally, to determine relative chiral abundances, the (n, m)-dependent Raman cross-sections must be considered and corrected. Jiang et al 128 and later Sato et al 129 calculated the exciton-photon and exciton-phonon coupling matrix elements for many (n, m), considering contributions of curvature, excitons and other many-body effects, to explain the chiral dependence of Raman intensity.…”

Section: Resonant Raman Scattering Spectroscopy Of Armchair-enricmentioning

confidence: 99%

Fundamental optical processes in armchair carbon nanotubes

Hároz

Duque

et al. 2013

Nanoscale

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Single-wall carbon nanotubes provide ideal model 1-D condensed matter systems in which to address fundamental questions in many-body physics, while, at the same time, they are leading candidates for building blocks in nanoscale optoelectronic circuits. Much attention has been recently paid to their optical properties, arising from 1-D excitons and phonons, which have been revealed via photoluminescence, Raman scattering, and ultrafast optical spectroscopy of semiconducting carbon nanotubes. On the contrary, dynamical properties of metallic nanotubes have been poorly explored, although they are expected to provide a novel setting for the study of electron-hole pairs in the presence of degenerate 1-D electrons. In particular, (n,n)-chirality, or armchair, metallic nanotubes are truly gapless with massless carriers, ideally suited for dynamical studies of Tomonaga-Luttinger liquids. Unfortunately, progress towards such studies has been slowed by the inherent problem of nanotube synthesis whereby both semiconducting and metallic nanotubes are produced. Here, we use post-synthesis separation methods based on density gradient ultracentrifugation and DNAbased ion-exchange chromatography to produce aqueous suspensions strongly enriched in armchair nanotubes. Through resonant Raman spectroscopy of the radial breathing mode phonons, we provide macroscopic and unambiguous evidence that density gradient ultracentrifugation can enrich armchair nanotubes. Furthermore, using conventional, optical absorption spectroscopy in the nearinfrared and visible range, we show that interband absorption in armchair nanotubes is strongly excitonic. Lastly, by examining the G-band mode in Raman spectra, we determine that observation of the broad, lower frequency (G − ) feature is a result of resonance with non-armchair "metallic" nanotubes. These findings regarding the fundamental optical absorption and scattering processes in metallic carbon nanotubes lay the foundation for further spectroscopic studies to probe many-body physical phenomena in one dimension.

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Quantifying carbon-nanotube species with resonance Raman scattering

Cited by 160 publications

References 16 publications

Gas phase synthesis of non-bundled, small diameter single-walled carbon nanotubes with near-armchair chiralities

Gas phase synthesis of non-bundled, small diameter single-walled carbon nanotubes with near-armchair chiralities

Scalable Method for the Reductive Dissolution, Purification, and Separation of Single-Walled Carbon Nanotubes

Fundamental optical processes in armchair carbon nanotubes

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