Dislocation theory of chirality-controlled nanotube growth

Ding, Feng; Harutyunyan, Avetik R.; Yakobson, Boris I.

doi:10.1073/pnas.0811946106

Cited by 311 publications

(419 citation statements)

References 35 publications

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“…Interestingly, our conclusion of chirality-dependent SWCNT growth rate for VPE is similar to that of Ding et al 37 for metal-catalysed SWCNT growth. This is because the armchair growth site in our model is equivalent to the 'kink' or 'cosy corner' in the model of Ding et al 37 It should be noted that there are alternative mechanisms proposed for graphene edge growth without a metal catalyst, such as hydrogen atom-catalysed addition of C 2 H 2 (ref. 38).…”

Section: What Is the Mechanism Of The Vpe-based Swcnt Cloning?supporting

confidence: 90%

Chirality-controlled synthesis of single-wall carbon nanotubes using vapour-phase epitaxy

et al. 2012

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Chirality-controlled synthesis of single-wall carbon nanotubes with predefined chiralities has been an important but elusive goal for almost two decades. Here we demonstrate a general strategy for producing carbon nanotubes with predefined chiralities by using purified singlechirality nanotubes as seeds for subsequent metal catalyst free growth, resembling vapourphase epitaxy commonly used for semiconductor films. In particular, we have successfully synthesized (7, 6), (6, 5) and (7, 7) nanotubes, and used Raman spectroscopy to show unambiguously that the original chiralities of the nanotube seeds are preserved. Furthermore, we have performed electrical measurements on synthesized individual (7, 6) and (6, 5) nanotubes, confirming their semiconducting nature. The vapour-phase epitaxy approach is found to be highly robust and should enable a wide range of fundamental studies and technological developments.

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Section: What Is the Mechanism Of The Vpe-based Swcnt Cloning?supporting

confidence: 90%

Chirality-controlled synthesis of single-wall carbon nanotubes using vapour-phase epitaxy

et al. 2012

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“…As well stated in the literature, the growing CNT has an open end attached to a stepped edge on a catalyst particle surface and the armchair (AC) sites are active for carbon insertion [19][20][21]. As shown in Figs.…”

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confidence: 75%

Efficient Defect Healing in Catalytic Carbon Nanotube Growth

et al. 2012

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“…However, it was recently elucidated that SWNTs grow by an axial screw dislocation that determines the rate of growth as well as the chirality of the SWNT that is produced. 34 Two categories of VLS that are relevant to nanotube synthesis are tip growth and base growth (Figure 1-4). 31 Specifically, if the catalyst particle is weakly attached to the substrate, it will ride along the developing tip of the SWNT during synthesis (tip growth); 19,35,36 on the other hand, growth will proceed from the SWNT base if the catalyst is strongly associated with the substrate (base growth).…”

Section: Growth Mechanism For Swntsmentioning

confidence: 99%

Photophysics of Individual Single-Walled Carbon Nanotubes

2008

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Single-walled carbon nanotubes (SWNTs) are cylindrical graphitic molecules that have remained at the forefront of nanomaterials research since 1991, largely due to their exceptional and unusual mechanical, electrical, and optical properties. The motivation for understanding how nanotubes interact with light (i.e., SWNT photophysics) is both fundamental and applied. Individual nanotubes may someday be used as superior near-infrared fluorophores, biological tags and sensors, and components for ultrahigh-speed optical communications systems. Establishing an understanding of basic nanotube photophysics is intrinsically significant and should enable the rapid development of such innovations. Unlike conventional molecules, carbon nanotubes are synthesized as heterogeneous samples, composed of molecules with different diameters, chiralities, and lengths. Because a nanotube can be either metallic or semiconducting depending on its particular molecular structure, SWNT samples are also mixtures of conductors and semiconductors. Early progress in understanding the optical characteristics of SWNTs was limited because nanotubes aggregate when synthesized, causing a mixing of the energy states of different nanotube structures. Recently, significant improvements in sample preparation have made it possible to isolate individual nanotubes, enabling many advances in characterizing their optical properties. In this Account, single-molecule confocal microscopy and spectroscopy were implemented to study the fluorescence from individual nanotubes. Single-molecule measurements naturally circumvent the difficulties associated with SWNT sample inhomogeneities. Intrinsic SWNT photoluminescence has a simple narrow Lorentzian line shape and a polarization dependence, as expected for a one-dimensional system. Although the local environment heavily influences the optical transition wavelength and intensity, single nanotubes are exceptionally photostable. In fact, they have the unique characteristic that their single molecule fluorescence intensity remains constant over time; SWNTs do not “blink” or photobleach under ambient conditions. In addition, transient absorption spectroscopy was used to examine the relaxation dynamics of photoexcited nanotubes and to elucidate the nature of the SWNT excited state. For metallic SWNTs, very fast initial recovery times (300–500 fs) corresponded to excited-state relaxation. For semiconducting SWNTs, an additional slower decay component was observed (50–100 ps) that corresponded to electron–hole recombination. As the excitation intensity was increased, multiple electron–hole pairs were generated in the SWNT; however, these e−h pairs annihilated each other completely in under 3 ps. Studying the dynamics of this annihilation process revealed the lifetimes for one, two, and three e−h pairs, which further confirmed that the photoexcitation of SWNTs produces not free electrons but rather one-dimensional bound electron–hole pairs (i.e., excitons). In summary, nanotube photophysics is a rapidly developing area o...

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Dislocation theory of chirality-controlled nanotube growth

Cited by 311 publications

References 35 publications

Chirality-controlled synthesis of single-wall carbon nanotubes using vapour-phase epitaxy

Chirality-controlled synthesis of single-wall carbon nanotubes using vapour-phase epitaxy

Efficient Defect Healing in Catalytic Carbon Nanotube Growth

Photophysics of Individual Single-Walled Carbon Nanotubes

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