Single-wall nanotubes produced by metal-catalyzed disproportionation of carbon monoxide

Dai, Hongjie; Rinzler, Andrew G.; Nikolaev, Pasha; Theß, Andreas; Colbert, Daniel T.; Smalley, R. E.

doi:10.1016/0009-2614(96)00862-7

Cited by 1,113 publications

(706 citation statements)

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“…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). 37,38 Atomic force microscopy (AFM) or TEM can elucidate whether the catalyst particle is situated at the tip or base of the SWNT during synthesis (Figure 1-4).…”

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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Section: Growth Mechanism For Swntsmentioning

confidence: 99%

Photophysics of Individual Single-Walled Carbon Nanotubes

2008

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“…In 1993, this kind of this structure called SWNTs was successful discovered by Iijima and Ichihashi [2]. After this step, there were a lot of reports and experimental studies on SWNTs in order to achieve this structure more productively, such as laser furnace (1996) [3], arc-discharge (1997) [4], chemical vapour deposition (CVD) with supported catalysts (1996) [5] and floated catalysts (1998) [6,7]. Although, these methods are good for mass synthesis of SWNT, purification processes are required.…”

Section: Organizationmentioning

confidence: 99%

“…Their method consist of producing SWNTs with chemical vapor deposition (CVD) [5], in which carbon monoxide (CO) was used as a carbon source for CVD growth that reacted with the metal catalyst particles inside a heated reactor. Because it's simple and controllable, this method became the most common used for SWNT production.…”

Section: Synthesis Of Swntsmentioning

confidence: 99%

“…The diameter control of SWNT with controlled structures has been studied by many researchers [3-5, 7, 22, and 47]. Among these methods, chemical vapor deposition (CVD) process is the dominate method for SWNT synthesis, which has a great potential in term of quantity and good control over the product [5]. Furthermore, SWNTs with small diameter (approximately 1 nm) have a larger band gap, and also are more mechanically stable than larger diameter SWNTs.…”

Section: Synthesis and Diameter Control Of Swntsmentioning

confidence: 99%

“…Co-Fe and Co-Rh binary catalysts can produce SWNTs that are similar in diameter, yet both of which are smaller than HiPco SWNTs. The SWNTs grown from these catalysts are dominant in (7,5) and (7,6) nanotubes, but SWNTs grown from Co-Rh can produce a bit more of (6, 5) nanotubes, which is identified from the intensity. The tendency for Co/Mo catalyst to produce SWNTs with a larger average diameter is in agreement with optical and resonance Raman spectra, however PLE indicates that SWNTs synthesized from Co-Mo catalyst on zeolite have a narrower diameter distribution than others, including HiPco.…”

Section: A New Noble Catalyst For Accvd Processmentioning

confidence: 99%

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