Determination of helicities in unidirectional assemblies of graphitic or graphiticlike tubular structures

Jiang, Han; Brown, David P.; Nikolaev, Pavel; Nasibulin, Albert G.; Kauppinen, Esko I.

doi:10.1063/1.2993217

Cited by 11 publications

(11 citation statements)

References 22 publications

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“…Nanotube EBD measurements have made a big leap forward since then [16], and these early pictures can now be interpreted as bundles with a range of chiral angles close to armchair structures. This generally agrees with recent EBD measurements on PLV nanotubes that show broad chiral angle distributions skewed towards armchair structures [17].…”

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confidence: 81%

Effect of the laser heating of nanotube nuclei on the nanotube type population

et al. 2009

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Many potential applications of carbon nanotubes are expected to beneÀt from the availability of single-walled À carbon nanotube materials enriched in metallic species, and specifically armchair nanotubes. The present work focuses on the modification of the pulsed laser vaporization (PLV) technique to selectively produce certain carbon nanotube structures. Nanotube nuclei were "warmed-up" with an additional laser pulse, timed to coincide approximately with the nucleation event. The effect of the second laser on the carbon vapor temperature was studied by emission spectroscopy. Nanotube type populations with and without warm-up were compared by means of absorption, photoluminescence, and Raman spectroscopy. It was found that the warm-up of nanotube nuclei with a laser pulse has a noticeable, albeit small, effect on the nanotube population. The intensity of spectral features associated with (9,7) nanotube and its large chiral angle neighbors increased, while small chiral angle nanotubes decreased, with exception of the (15,0) tube. This experiment demonstrates that nanotube population during PLV synthesis can be manipulated in a controlled fashion. KEYWORDSNanotube synthesis, pulsed laser vaporization, nanotube population. Nano ResearchAs with other nanomaterials, the electronic properties of single-walled carbon nanotubes (SWCNTs) strongly depend on their size and molecular structure, which can be conveniently expressed in terms of chiral indices (n, m) [1]. Nanotubes with n = m (armchair nanotubes) are metallic at room temperature while those with n m = 3j 3 , (j ( = 1, 2, 3…) are strictly semi-metals, but often called metals along with armchairs. Nanotubes with n m = 3j 3 + 1 and n m = 3j 3 + 2 (j ( = 0, 1, 2, 3…) are semiconductors with a band gap that varies approximately inversely with diameter. Metallic and semi-metallic nanotubes exhibit singularities in the electron density of states similar to semiconducting ones, with corresponding optical transition energies inversely proportional to the diameter.Such wealth of available electronic properties presents many opportunities to utilize SWCNTs 819 Nano Res (2009) 2: 818 827 in various applications, such as field emission sources, transistors, interconnects on microchips, conductive transparent films, and photovoltaics [2 7]. Most of these applications will benefit from use of certain (n,m) nanotube types (metallic, small gap semiconductor, etc.) However, as-produced SWCNT samples are polydisperse, with many (n,m) types present and typical metal/semiconductor ratios of ~1:2. This lack of specificity in SWCNT samples is one of the primary reasons why they are rarely used in commercial applications today. An ability to "tweak the knobs" on the SWCNT synthesis set-up to produce a desired narrow range of (n,m) structures would greatly simplify the costly type separation [8], or even render it unnecessary. However, it seems that the only "knob" that has been touched so far is the synthesis temperature. The best known example is low temperature CoMoCat SWCN...

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confidence: 81%

Effect of the laser heating of nanotube nuclei on the nanotube type population

et al. 2009

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“…The chiral indices, ( n , m ), of all the three shells at any cross section in the TWNT could be determined accurately (see the Supportin Information, Fig. S7–S9) 22, 23. The results show that this TWNT maintains a constant chiral index for each shell through the length of 25 to 60 mm (electron diffraction patterns of these two positions were shown in Fig.…”

Section: Chiral Indices Diameters and Chiral Angles Of Eight Twnts Wmentioning

confidence: 82%

100 mm Long, Semiconducting Triple‐Walled Carbon Nanotubes

et al. 2010

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Direct growth of 100 mm long, semiconducting triple‐walled carbon nanotubes (TWNTs) on Si substrates by chemical vapor depoistion is reported. By tailoring the temperature for a certain gas flow rate, a yield of nearly 90% of centimeter‐long TWNTs is obtained. The TWNTs show an unprecedented structural homogeneity, in which each shell maintains a constant chiral index extending over a very large distance (>60 mm). The semiconducting TWNTs can be directly fabricated into field‐effect transistors.

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“…A-priori this grouping is unknown. However, Jiang et al showed that d2 and d3 belonging to the same layer of a MWNT should form a conjugated pair [48] with the following property: the bigger d3, the less is d2, and vice versa. Based on this principle, Deniz et al proposed a zone method for the accurate grouping of layer-lines [49].…”

Section: Measuring Axial Positions Of Layer-linesmentioning

confidence: 99%

Accurate determination of the chiral indices of individual carbon nanotubes by combining electron diffraction and Resonant Raman spectroscopy

Levshov

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Paillet

et al. 2017

Carbon

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The experimental approach combining high resolution transmission electron microscopy (HRTEM), electron diffraction (ED) and resonant Raman spectroscopy (RRS) on the same freestanding individual carbon nanotubes (CNT) is the most efficient method to determine unambiguously the intrinsic features of the Raman-active phonons. In this paper, we review the main results obtained by the approach regarding the intrinsic features of the phonons of singlewalled (SWNT) and double-walled carbon nanotubes (DWNT). First, we detail the different methods to identify the structure of SWNTs and DWNTs from the analysis of their electron diffraction patterns (EDP). In the following, we remind the principal features of the Raman response of SWNTs, unambiguously index-identified by ED. A special attention is devoted to the effect of the inter-layer interaction on the frequencies of the Raman-active phonons in indexidentified DWNTs. The information obtained on index-identified SWNT and DWNT allows us to propose Raman criteria, which help identifying CNT when the ED fails to propose a single assignment. The efficiency of the Raman criteria as the complement to the ED information for the index-assignment of a few SWNTs and DWNTs is shown. The same approach to index-assign a triple-walled carbon nanotube (TWNT), by combining ED and RRS information, is reported.

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Determination of helicities in unidirectional assemblies of graphitic or graphiticlike tubular structures

Cited by 11 publications

References 22 publications

Effect of the laser heating of nanotube nuclei on the nanotube type population

Effect of the laser heating of nanotube nuclei on the nanotube type population

100 mm Long, Semiconducting Triple‐Walled Carbon Nanotubes

Accurate determination of the chiral indices of individual carbon nanotubes by combining electron diffraction and Resonant Raman spectroscopy

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