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1

Process for Separating Metallic from Semiconducting Single-Walled Carbon Nanotubes.  

National Technical Information Service (NTIS)

A method for separating semiconducting single-walled carbon nanotubes from metallic single-walled carbon nanotubes is disclosed. The method utilizes separation agents that preferentially associate with semiconducting nanotubes due to the electrical nature...

Y. P. Sun

2004-01-01

2

Molecular dynamics simulation of metal coating on single-walled carbon nanotube  

NASA Astrophysics Data System (ADS)

Behaviors of various metals coating on single-walled carbon nanotubes are simulated by molecular dynamics. Some of the potential parameter sets are derived by DFT calculations. The results indicate that each metal species can be smoothly coated on an isolated carbon nanotube, depending on the coating condition; however, continuous coating may not always be possible. The equilibrium position on the carbon nanotube is fixed; therefore, the coating is discontinuous for a large sized atom to reduce the distortion. The diffusion rate of the metal atoms is expressed in terms of the ratios of the binding energies of metal-metal and metal-carbon bonds.

Inoue, Shuhei; Matsumura, Yukihiko

2008-10-01

3

Assessment of Damping Mechanisms Effect on High Frequency Transmission Behavior of Metallic Single Walled Carbon Nanotubes  

Microsoft Academic Search

In this paper, quantum theory in combination with classical distributed transmission line model, is utilized to predict the dynamical behavior of a metallic single walled carbon nanotube (SWCNT) in transmitting high frequency energy. SWCNT is treated as a nano transmission line and a novel modified model is assumed to consider the effect of nanotubes length and account for possible damping

M. Saeed Tahvili; N. S. Jahanmiri; M. Hossein Sheikhi

2007-01-01

4

Electron-Phonon Scattering in Metallic Single-Walled Carbon Nanotubes  

Microsoft Academic Search

Electron scattering rates in metallic single-walled carbon nanotubes are studied using an atomic force microscope as an electrical probe. From scaling of the resistance of the same nanotube with length in the low and high bias regimes, the mean free paths for both regimes are inferred. The observed scattering rates are consistent with calculations for acoustic phonon scattering at low

Sami Rosenblatt; Yuval Yaish; Vera Sazonova; Hande Ustunel; Stephan Braig; Tomas A. Arias; Piet W. Brouwer; Paul L. McEuen

2004-01-01

5

A Field Effect Transistor Fabricated with Metallic Single?Walled Carbon Nanotubes  

Microsoft Academic Search

We report novel transport properties of the individual single?walled carbon nanotube (SWNT) field effect transistors (FETs) decorated with the protein (streptavidin)?coated nanoparticles. Upon adsorption of the protein?coated nanoparticles at the metal?nanotube contact, the metallic SWNT devices abruptly exhibit a p?type semiconducting behavior. In the case of semiconducting SWNT devices, the adsorptions of protein?coated nanoparticles make the gating more effective, resulting

Pil Sun Na; Jinhee Kim; Hyojin Kim; Hyunju Chang

2006-01-01

6

Dependence of Raman spectra G' band intensity on metallicity of single-wall carbon nanotubes  

Microsoft Academic Search

We report the peculiar behavior of the G' band Raman intensity, which is dependent on the metallicity of single-wall carbon nanotubes (SWCNTs). In the metallic SWCNTs, the G' band intensity was enhanced relative to the G band intensity, while the G' band intensity was suppressed in the semiconducting SWCNTs. Resonance Raman spectroscopy (using laser energies of Elaser=2.41 , 1.96, 1.58,

Ki Kang Kim; Jin Sung Park; Sung Jin Kim; Hong Zhang Geng; Kay Hyeok An; Cheol-Min Yang; Kentaro Sato; Riichiro Saito; Young Hee Lee

2007-01-01

7

Dependence of the Raman G' band intensity on metallicity of single-wall carbon nanotubes  

Microsoft Academic Search

We report the peculiar behavior of the G'-band Raman intensity, which is dependent on the metallicity of single-wall carbon nanotubes (SWCNTs). In the metallic SWCNTs, the G'-band intensity was enhanced relative to the G-band intensity, while the G'-band intensity was suppressed in the semiconducting SWCNTs. Resonance Raman spectroscopy (using laser energies of Elaser = 2.41 eV, 1.96 eV, 1.58 eV,

Ki Kang Kim; Jin Sung Park; Sung Jin Kim; Hong Zhang Geng; Kay Hyeok An; Cheol-Min Yang; Kentaro Sato; Riichiro Saito; Young Hee Lee

2008-01-01

8

Characterization and estimation of tunnel barrier height in metallic single-wall carbon nanotube quantum dots  

Microsoft Academic Search

A tunnel barrier height has been estimated in quantum dots (QDs) formed in metallic single-wall carbon nanotubes (SWNTs), where QDs can be fabricated simply by depositing metallic contacts on top of the nanotube. Transport measurements have been carried out in a temperature range between 1.5 and 300K, and revealed single and multi-QD behaviors in different samples at low temperatures. The

D. Tsuya; M. Suzuki; Y. Aoyagi; K. Ishibashi

2005-01-01

9

Direct identification of metallic and semiconducting single-walled carbon nanotubes in scanning electron microscopy.  

PubMed

Because of their excellent electrical and optical properties, carbon nanotubes have been regarded as extremely promising candidates for high-performance electronic and optoelectronic applications. However, effective and efficient distinction and separation of metallic and semiconducting single-walled carbon nanotubes are always challenges for their practical applications. Here we show that metallic and semiconducting single-walled carbon nanotubes on SiO(2) can have obviously different contrast in scanning electron microscopy due to their conductivity difference and thus can be effectively and efficiently identified. The correlation between conductivity and contrast difference has been confirmed by using voltage-contrast scanning electron microcopy, peak force tunneling atom force microscopy, and field effect transistor testing. This phenomenon can be understood via a proposed mechanism involving the e-beam-induced surface potential of insulators and the conductivity difference between metallic and semiconducting SWCNTs. This method demonstrates great promise to achieve rapid and large-scale distinguishing between metallic and semiconducting single-walled carbon nanotubes, adding a new function to conventional SEM. PMID:22730928

Li, Jie; He, Yujun; Han, Yimo; Liu, Kai; Wang, Jiaping; Li, Qunqing; Fan, Shoushan; Jiang, Kaili

2012-07-03

10

Electrical and thermal transport in metallic single-wall carbon nanotubes on insulating substrates  

Microsoft Academic Search

We analyze transport in metallic single-wall carbon nanotubes (SWCNTs) on insulating substrates over the bias range up to electrical breakdown in air. To account for Joule self-heating, a temperature-dependent Landauer model for electrical transport is coupled with the heat conduction equation along the nanotube. The electrical breakdown voltage of SWCNTs in air is found to scale linearly with their length,

Eric Pop; David A. Mann; Kenneth E. Goodson; Hongjie Dai

2007-01-01

11

Transition of single-walled carbon nanotubes from metallic to semiconducting in field-effect transistors by hydrogen plasma treatment.  

PubMed

We report hydrogen plasma treatment results on converting the metallic single-walled carbon nanotubes to semiconducting single-walled carbon nanotubes. We found that the as-grown single-walled carbon nanotubes (SWNTs) can be sorted as three groups which behave as metallic, as-metallic, and semiconducting SWNTs. These three groups have different changes under hydrogen plasma treatment and successive annealing process. The SWNTs can be easily hydrogenated in the hydrogen plasma environment and the as-metallic SWNTs can be transformed to semiconducting SWNTs. The successive annealing process can break the C-H bond, so the conversion is reversible. PMID:17508771

Zheng, Gang; Li, Qunqing; Jiang, Kaili; Zhang, Xiaobo; Chen, Jia; Ren, Zheng; Fan, Shoushan

2007-05-18

12

Synthesis of single-walled carbon nanotube\\/metal nanoparticle hybrid materials from potassium-filled nanotubes  

Microsoft Academic Search

The reducing property of potassium-filled single-walled carbon nanotubes (SWCNTs) was used to synthesize single-walled carbon nanotube\\/metal nanoparticle hybrid materials. Electron transfer from potassium to SWCNTs gives rise to a substantial enhancement of the reducing ability of the carbon nanotubes. Metal ions with redox potentials lower than that of pristine SWCNTs can be reduced by potassium-filled SWCNTs. SWCNTs decorated with copper

Zhiyong Wang; Zujin Shi; Zhennan Gu

2010-01-01

13

Non-adiabatic phonon dispersion of metallic single-walled carbon nanotubes  

Microsoft Academic Search

Non-adiabatic effects can considerably modify the phonon dispersion of low-dimensional metallic systems. Here, these effects\\u000a are studied for the case of metallic single-walled carbon nanotubes using a perturbative approach within a density-functional-based\\u000a non-orthogonal tight-binding model. The adiabatic phonon dispersion was found to have logarithmic Kohn anomalies at the Brillouin\\u000a zone center and at two mirror points inside the zone. The

Valentin N. Popov; Philippe Lambin

2010-01-01

14

Photogenerated Free Carrier Dynamics in Metal and Semiconductor Single-Walled Carbon Nanotube Films  

SciTech Connect

Time-resolved THz spectroscopy (TRTS) is employed to study the photogenerated charge-carrier dynamics in transparent films of single-walled carbon nanotubes (SWNTs). Two films were investigated: a film with 94% semiconducting-type tubes (s-SWNTs) and a film with only 7% s-SWNT and 93% metal-type tubes (m-SWNTs). We conclude that charge-carriers are generated with >60% yields at low light intensities in both films. Free-carriers are generated by a linear exciton dissociation process that occurs within 1 ps and is independent of excitation wavelength or tube type.

Beard, M. C.; Blackburn, J. L.; Heben, M. J.

2008-01-01

15

Photogenerated free carrier dynamics in metal and semiconductor single-walled carbon nanotube films.  

PubMed

Time-resolved THz spectroscopy (TRTS) is employed to study the photogenerated charge-carrier dynamics in transparent films of single-walled carbon nanotubes (SWNTs). Two films were investigated: a film with 94% semiconducting-type tubes (s-SWNTs) and a film with only 7% s-SWNT and 93% metal-type tubes (m-SWNTs). We conclude that charge-carriers are generated with >60% yields at low light intensities in both films. Free-carriers are generated by a linear exciton dissociation process that occurs within -1 ps and is independent of excitation wavelength or tube type. PMID:19367928

Beard, Matthew C; Blackburn, Jeffrey L; Heben, Michael J

2008-12-01

16

Bound excitons and optical absorption spectra of (10,10) metallic single-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

Motivated by recent theoretical prediction of bound excitons [1] in small diameter metallic single-walled carbon nanotubes, we study the optical spectra of the larger diameter (10,10) metallic tube. We use an interacting-particle Green’s function approach which includes calculations of the quasiparticle excitation spectrum (within the GW approximation for the electron self energy) and the electron-hole excitation spectrum (within the Bethe-Salpeter formalism). We show that the (10,10) tube has important excitonic effects despite being a metal, due to the quasi-one dimensional nature of the carbon nanotubes. A bound exciton with binding energy of 60 meV is found, and the location of the excitonic peak in the optical spectrum is at 1.8 eV. [1] C. D. Spataru, S. Ismail-Beigi, L. X. Benedict, and S. G. Louie, Phys. Rev. Lett. 92, 077402 (2004).

Deslippe, Jack; Spataru, Catalin; Louie, Steven

2006-03-01

17

Effect of doping on single-walled carbon nanotubes network of different metallicity  

PubMed Central

Effects of doping on single-walled carbon nanotubes (SWNT) networks with different metallicity are reported through the study of sheet resistance changes upon annealing and acid treatment. SWNT film with high metallic tube content is found to have relatively good chemical stability against post treatments, as demonstrated from its stable film performance in ambient after annealing, and merely 15% reduction in sheet resistance upon sulfuric acid treatment. Conversely, film stability of SWNT film with low metallic content which comprises largely of semiconducting SWNT varies with days in ambient, and its sheet resistance changes drastically after treated with acid, indicating the extreme sensitivity of semiconducting SWNT to surrounding environment. The results suggest that annealing removes unintentional oxygen doping from the ambient and shifts the Fermi level towards the intrinsic Fermi level. Acid treatment, on the other hand, introduces physisorbed and chemisorbed oxygen and shifts the Fermi level away from the intrinsic level and increases the hole doping.

2012-01-01

18

Metal-Assisted Hydrogen Storage on Pt-Decorated Single-Walled Carbon Nanohorns  

SciTech Connect

The catalytic dissociation of hydrogen molecules by metal nanoparticles and spillover of atomic hydrogen onto various supports is a well-established phenomenon in catalysis. However, the mechanisms by which metal catalyst nanoparticles can assist in enhanced hydrogen storage on high-surface area supports are still under debate. Experimental measurements of metal-assisted hydrogen storage have been hampered by inaccurate estimation of atomically stored hydrogen deduced from comparative measurements between metal-decorated and undecorated samples. Here we report a temperature cycling technique combined with inelastic neutron scattering (INS) measurements of quantum rotational transitions of molecular H2 to more accurately quantify adsorbed hydrogen aided by catalytic particles using single samples. Temperature cycling measurements on single-wall carbon nanohorns (SWCNHs) decorated with 2-3 nm Pt nanoparticles showed 0.17 % mass fraction of metal-assisted hydrogen storage (at 0.5 MPa) at room temperature. Temperature cycling of Pt-decorated SWCNHs using a Sievert s apparatus also indicated metal-assisted hydrogen adsorption of 0.08 % mass fraction at 5 MPa at room temperature. No additional metal-assisted hydrogen storage was observed in SWCNH samples without Pt nanoparticles cycled to room temperature, or in Pt-SWCNHs when the temperature was cycled to less than 150K. The possible formation of C-H bonds due to spilled-over atomic hydrogen was also investigated using both INS and density functional theory calculations.

Liu, Yun [National Institute of Standards and Technology (NIST); Brown, Craig [National Institute of Standards and Technology (NIST); Neumann, Dan [National Institute of Standards and Technology (NIST); Geohegan, David B [ORNL; Puretzky, Alexander A [ORNL; Rouleau, Christopher M [ORNL; Hu, Hui [ORNL; Styers-Barnett, David J [ORNL; Krasnov, Pavel O. [Rice University; Yakobson, Boris I. [Rice University

2012-01-01

19

Hydrogen adsorption measurements and modeling on metal-organic frameworks and single-walled carbon nanotubes.  

PubMed

Hydrogen adsorption measurements on Al-, Cr-, and Zn-based metal-organic frameworks (MOFs) and single-walled carbon nanotubes (SWNTs) are presented. The measurements were performed at temperatures ranging from 77 to 300 K and pressures up to 50 atm using a volumetric approach. The maximum excess adsorption at 77 K ranges from 2.3 to 3.9 wt % for the MOFs and from 1.5 to 2.5 wt % for the SWNTs. These values are reached at pressures below 40 atm. At room temperature and 40 atm, modest amounts of hydrogen are adsorbed (<0.4 wt %). A Dubinin-Astakhov (DA) approach is used to investigate the measured adsorption isotherms and to retrieve energetic and structural parameters. The adsorption enthalpy averaged over filling is about 2.9 kJ/mol for the MOF-5 and about 3.6-4.2 kJ/mol for SWNTs. PMID:17014118

Poirier, E; Chahine, R; Bénard, P; Lafi, L; Dorval-Douville, G; Chandonia, P A

2006-10-10

20

The effect of single wall carbon nanotube metallicity on genomic DNA-mediated chirality enrichment  

NASA Astrophysics Data System (ADS)

Achieving highly enriched single wall carbon nanotubes (SWNTs) is one of the major hurdles today because their chirality-dependent properties must be uniform and predictable for use in nanoscale electronics. Due to the unique wrapping and groove-binding mechanism, DNA has been demonstrated as a highly specific SWNT dispersion and fractionation agent, with its enrichment capabilities depending on the DNA sequence and length as well as the nanotube properties. Salmon genomic DNA (SaDNA) offers an inexpensive and scalable alternative to synthetic DNA. In this study, SaDNA enrichment capabilities were tested on SWNT separation with varying degrees of metallicity that were formulated from mixtures of commercial metallic (met-) and semiconducting (sem-) abundant SWNTs. The results herein demonstrate that the degree of metallicity of the SWNT sample has a significant effect on the SaDNA enrichment capabilities, and this effect is modeled based on deconvolution of the near-infrared (NIR) absorption spectra and verified with photoluminescence emission (PLE) measurements. Using molecular dynamics and circular dichroism, the preferential SaDNA mediated separation of the (6, 5) sem-tube is shown to be largely influenced by the presence of met-SWNTs.Achieving highly enriched single wall carbon nanotubes (SWNTs) is one of the major hurdles today because their chirality-dependent properties must be uniform and predictable for use in nanoscale electronics. Due to the unique wrapping and groove-binding mechanism, DNA has been demonstrated as a highly specific SWNT dispersion and fractionation agent, with its enrichment capabilities depending on the DNA sequence and length as well as the nanotube properties. Salmon genomic DNA (SaDNA) offers an inexpensive and scalable alternative to synthetic DNA. In this study, SaDNA enrichment capabilities were tested on SWNT separation with varying degrees of metallicity that were formulated from mixtures of commercial metallic (met-) and semiconducting (sem-) abundant SWNTs. The results herein demonstrate that the degree of metallicity of the SWNT sample has a significant effect on the SaDNA enrichment capabilities, and this effect is modeled based on deconvolution of the near-infrared (NIR) absorption spectra and verified with photoluminescence emission (PLE) measurements. Using molecular dynamics and circular dichroism, the preferential SaDNA mediated separation of the (6, 5) sem-tube is shown to be largely influenced by the presence of met-SWNTs. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr00458a

Kim, Steve S.; Hisey, Colin L.; Kuang, Zhifeng; Comfort, Donald A.; Farmer, Barry L.; Naik, Rajesh R.

2013-05-01

21

Electrical and thermal transport in metallic single-wall carbon nanotubes on insulating substrates  

NASA Astrophysics Data System (ADS)

We analyze transport in metallic single-wall carbon nanotubes (SWCNTs) on insulating substrates over the bias range up to electrical breakdown in air. To account for Joule self-heating, a temperature-dependent Landauer model for electrical transport is coupled with the heat conduction equation along the nanotube. The electrical breakdown voltage of SWCNTs in air is found to scale linearly with their length, approximately as 5 V/?m we use this to deduce a thermal conductance between SWCNT and substrate g~0.17+/-0.03 W K-1 m-1 per tube length, which appears limited by the SWCNT-substrate interface rather than the thermal properties of the substrate itself. We examine the phonon scattering mechanisms that limit electron transport, and find the strong temperature dependence of the optical phonon absorption rate to have a remarkable influence on the electrical resistance of micron-length nanotubes. Further analysis reveals that unlike in typical metals, electrons are responsible for less than 15% of the total thermal conductivity of metallic nanotubes around room temperature, and this contribution decreases at high bias or higher temperatures. For interconnect applications of metallic SWCNTs, significant self-heating may be avoided if power densities are limited below 5 ?W/?m, or if the SWCNT-surrounding thermal interface is optimized.

Pop, Eric; Mann, David A.; Goodson, Kenneth E.; Dai, Hongjie

2007-05-01

22

Preferential etching of metallic single-walled carbon nanotubes with small diameter by fluorine gas  

NASA Astrophysics Data System (ADS)

We have introduced a new approach to selectively remove metallic single-walled carbon nanotubes (SWCNTs) using a gas phase reaction by fluorine gas, followed by a heat treatment. The metallicity of the treated samples was characterized by the resonant Raman spectra with three wavelengths of 514, 633, and 785nm and UV-visible-NIR absorption spectra. Peaks of metallic SWCNTs with small diameters less than 1.1nm in the radial breathing mode of Raman spectra were greatly suppressed with fluorination and completely disappeared after heat treatment. On the other hand, the semiconducting SWCNTs with small diameters less than 1.1nm were still retained after fluorination. Moreover, the D-band decreased after annealing at 900°C , which was associated with the release of fluorine atoms during heat treatment. The removal of metallic SWCNTs was not observed at SWCNTs with diameters greater than 1.1nm . The absorption data also demonstrated the similar diameter dependence in the selectivity to the Raman spectra.

Yang, Cheol-Min; An, Kay Hyeok; Park, Jin Sung; Park, Kyung Ah; Lim, Seong Chu; Cho, Se-Ho; Lee, Young Seak; Park, Wanjun; Park, Chong Yun; Lee, Young Hee

2006-02-01

23

Curvature induced gaps and pseudo gaps in metallic single-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

Single-walled carbon nanotubes (SWNTs) with indices (n,n+3q) (q is an integer) should behave as metallic quantum wires based on a graphene sheet model. However, finite curvature of the graphene sheet in nanotubes and broken rotational symmetry, which could arise from interactions with adjacent tubes or surfaces, could open gaps in the density of states at the Fermi energy (E_F). This presentation will focus on recent low temperature scanning tunneling microscopy (STM) studies of intrinsic small gaps in SWNTs. Our data show that small diameter "metallic" zigzag tubes have true gaps at E_F, and that the gap magnitude is inversely proportional to the square of the tube radius. An explicit Fermi-vector shifting model has been developed to provide quantitative insight into the observed gaps. In addition, our studies have found that armchair SWNTs in bundles exhibit pseudo gaps at E_F, while isolated armchair tubes do not exhibit gap-like features. The magnitude of the pseudo gap was found to exhibit a weak inverse dependence on tube radius. The magnitude and radius dependence has been compared with theoretical predictions. The presence of these intrinsic small energy gaps demonstrate that most "metallic" SWNTs are not true one dimensional (1D) metals, and thus should have an important impact on our understanding of the electronic properties of SWNTs and related nanoelectronic devices.

Ouyang, Min

2001-03-01

24

Aharonov Bohm differential conductance modulation in defective metallic single-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

Using a perturbative approach, the effects of the energy gap induced by the Aharonov-Bohm (AB) flux on the transport properties of defective metallic single-walled carbon nanotubes (MSWCNTs) are investigated. The electronic waves scattered back and forth by a pair of impurities give rise to Fabry-Perot oscillations which constitutes a coherent backscattering interference pattern (CBSIP). It is shown that the CBSIP can be aperiodically modulated by applying a magnetic field parallel to the nanotube axis. In fact, the AB-flux brings this CBSIP under control by an additional phase shift. As a consequence, the extrema as well as zeros of the CBSIP are located at the irrational fractions of the quantity ?? = ?/?0, where ? is the flux piercing the nanotube cross section and ?0 = h/e is the magnetic quantum flux. Indeed, the spacing between two adjacent extrema in the magneto-differential conductance (MDC) profile is decreased with increasing magnetic field. The faster and higher and slower and shorter variations are then obtained by metallic zigzag and armchair nanotubes, respectively. Such results lead to the proposal that defective metallic nanotubes could be used as magneto-conductance switching devices based on the AB effect.

Bagheri, Mehran

2008-02-01

25

Covalent sidewall functionalization of single-walled carbon nanotubes via reduction of benzophenone by potassium metal  

Microsoft Academic Search

Covalent sidewall functionalization of single-walled carbon nanotubes (SWNTs) via addition of diphenylcarbinol (DPC) anions and diphenylcarbinol radicals was reported. The reaction of a potassium atom with a benzophenone molecule results in transferring one electron from the potassium to the benzophenone, forming a radical which adds readily to nanotubes to form functionalized SWNTs (DPC-SWNTs). DPC anions were generated from two- electrons

Liangming Wei; Zijiong Li; Yafei Zhang

2008-01-01

26

Evaluation of metallic and semiconducting single-walled carbon nanotube characteristics.  

PubMed

The nature of the mixed electronic type metallic (M-) and semiconducting (S-) single-walled carbon nanotubes (SWNTs) synthesized by current methods has posed a key challenge for the development of high performance SWNT-based electronic devices. The precise measurements of M- to S-SWNT ratio in as-grown or separated samples are of paramount importance for the controlled synthesis, separation and the realization of various applications. The objective of this review is to provide comprehensive overview of the progress achieved so far for measuring the M/S ratio both on individual and collective levels of SWNT states. We begin with a brief introduction of SWNT structures/properties and discussion of the problems and difficulties associated with precise measurement of the M/S ratio, and then introduce the principles for obtaining distinguished signals from M-and S-SWNTs. These techniques are classified into different groups based either on the single/ensemble detection of SWNT samples or on the principles of techniques themselves. We then present the M/S ratio evaluation results of these methods, with emphasis on scanning probe microscopy (SPM)-based detection techniques. Finally, the prospects of precise and large-scale measurement of M/S ratio in achieving controlled synthesis and understanding growth mechanism of SWNTs are discussed. PMID:21387025

Wu, Bin; Geng, Dechao; Liu, Yunqi

2011-03-08

27

Metal-insulator transition in doped single-wall carbon nanotubes  

NASA Astrophysics Data System (ADS)

We find strong evidence for a metal-insulator (MI) transition in macroscopic single wall carbon nanotube (SWNT) conductors. This is revealed by systematic measurements of resistivity and transverse magnetoresistance (MR) in the ranges 1.9-300 K and 0-9 Tesla, as a function of p -type redox doping. Strongly H2SO4 -doped samples exhibit small negative MR, and the resistivity is low and only weakly temperature-dependent. Stepwise dedoping by annealing in vacuum induces a MI transition. Critical behavior is observed near the transition, with ?(T) obeying a power-law temperature dependence, ?(T)?T-? . In the insulating regime (high annealing temperatures), the ?(T) behavior ranges from Mott-like three-dimensional (3D) variable-range hopping (VRH), ?(T)?exp[(T0/T)-1/4] , to Coulomb-gap (CGVRH) behavior, ?(T)?exp[(-T0/T)-1/2] . Concurrently, MR (B) becomes positive for large B , exhibiting a minimum at magnetic field Bmin . The temperature dependence of Bmin can be characterized by Bmin(T)=Bc(1-T/Tc) for a large number of samples prepared by different methods. Below a sample-dependent crossover temperature Tc , MR (B) is positive for all B . The observed changes in transport properties are explained by the effect of doping on semiconducting SWNTs and tube-tube coupling.

Vavro, J.; Kikkawa, J. M.; Fischer, J. E.

2005-04-01

28

Annealing single-walled metallic carbon nanotube devices in ultra-high vacuum  

NASA Astrophysics Data System (ADS)

Single walled carbon nanotube (SWNT) devices were fabricated and annealed in ultra high vacuum (UHV) with simultaneous electrical characterization. As one-dimensional crystals with nanometer scale diameters and up to meter scale lengths, SWNTs offer a unique opportunity to probe 1D transport in mesoscopic electronics. Furthermore, all of the atoms in SWNTs are surface atoms which means that the electronic properties can be examined and tailored using the well-developed tools of surface chemistry. However, electronic resistances and noise for technologically relevant small-diameter SWNT devices are too high for commercial applications. In this work, intrinsic and extrinsic sources of scattering in SWNTs were examined by heating SWNT field effect transistors in UHV with while monitoring changes in the devices' resistance, transconductance, and conductance fluctuations. The effects of the contact interface were studied by varying the electrode metal, including palladium, titanium, and platinum contacts. It was found that metal-SWNT contact interfaces are the primary scatterers in devices as fabricated, but the contact resistance can be greatly reduced by annealing to a limit that depends primarily on the surface chemistry of the electrode metal and the geometry of the interface. Secondary sources of scattering include surface adsorbates on the electrodes and substrate, sub-strate oxide phonons and SWNT phonons. Adsorbates are the primary source of 1/f conductance noise, followed by the electrode interface. Annealing devices in UHV was found to reduce the contact resistance, noise, and device to device inhomogeneity. Graphene, formed through catalysis on the Pt surface during the anneal, was found to make the best contact to SWNTs, rather than the conventional Pd, Ti, and Pt, both in terms of contact resistance and noise.

Kane, Alexander Allen

29

Thin-film metal catalyst for the production of multi-wall and single-wall carbon nanotubes  

Microsoft Academic Search

We present a detailed study of the growth of multiwall and single-wall carbon nanotubes (SWCNTs) by chemical-vapor deposition using a thin-film triple metal (Al\\/Fe\\/Mo) catalyst. Using Nanoauger spectroscopy, a full map of the metals in the sample surface is constructed and their evolution followed at different deposition temperatures. During the formation of SWCNTs at high temperatures (~1000 °C), the initial

R. G. Lacerda; K. B. K. Teo; A. S. Teh; M. H. Yang; S. H. Dalal; D. A. Jefferson; J. H. Durrell; N. L. Rupesinghe; D. Roy; G. A. J. Amaratunga; W. I. Milne; F. Wyczisk; P. Legagneux; M. Chhowalla

2004-01-01

30

Photo-physics of P3HT blended with highly enriched metallic and semiconducting single-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

Single-walled carbon nanotubes (SWNTs) possess unique properties that may potentially benefit photovoltaic (PV) devices, including high carrier mobilities, convenient work functions, and tunable optical transitions that span most of the solar spectrum. However, significant polydispersity in both diameter and electronic structure have hindered the realization of efficient PV cells incorporating SWNTs. In this presentation, we report the use of advanced techniques to separate single-walled carbon nanotubes (SWNTs) created by laser vaporization into highly enriched semiconducting and metallic species. The enriched SWNTs are then blended with regioregular poly(3-hexylthiophene) (P3HT) to serve as a model electron donor/acceptor system, analogous to systems typically used in organic PV devices. We investigate the photo-physical properties of charge generation and transfer using primarily time-resolved microwave conductivity (TRMC) and photoluminescence excitation spectroscopy and discuss the disparities between metallic vs semiconducting SWNT acceptors.

Holt, Josh; Mistry, Kevin; Ferguson, Andrew; Blackburn, Jeff

2010-03-01

31

Metallic and semiconducting single-walled carbon nanotubes: differentiating individual SWCNTs by their carbon 1s spectra.  

PubMed

The C 1s inner shell excitation spectra of individual metallic and semiconducting single-walled carbon nanotubes (SWCNTs) were measured using high-resolution electron energy loss spectroscopy in an aberration-corrected transmission electron microscope (TEM-EELS). On the basis of its diameter, the metallic SWCNT is most likely a (10,10) sample, whereas (11,12) and a number of other chiral vectors are consistent with the diameter of the semiconducting SWCNTs. The C 1s X-ray absorption spectra of the same electronically pure SWCNT materials were measured as individual bundles or agglomerations of bundles by scanning transmission X-ray microscopy. Spectral differences in the C 1s ? ?* transitions of metallic and semiconducting species, related to differences in the van Hove singularities in their unoccupied states, are observed by both methods. The fine structure of the C 1s ? ?* transitions is similar to that recently reported from nonspatially resolved X-ray absorption spectroscopy of ensemble samples of high-purity metallic and semiconducting SWCNTs. The quality of the TEM-EELS spectra of individual SWCNTs is such that the line shape can be used to identify if they are metallic or semiconducting, thereby opening up the possibility to interrogate the electronic state of single-SWCNT devices. A strong X-ray linear dichroism in the C 1s ? ?* band of both types of SWCNTs was observed. PMID:23176188

Rossouw, David; Botton, Gianluigi A; Najafi, Ebrahim; Lee, Vincent; Hitchcock, Adam P

2012-11-29

32

Alloy hydride catalyst route for the synthesis of single-walled carbon nanotubes, multi-walled carbon nanotubes and magnetic metal-filled multi-walled carbon nanotubes  

Microsoft Academic Search

This paper presents a novel, cost-effective and single-step technique for the synthesis of single-walled carbon nanotubes (SWNTs), multi-walled carbon nanotubes (MWNTs) and magnetic metal-filled MWNTs using a fixed bed reaction thermal chemical vapour deposition (CVD) using alloy hydride catalyst. The single-step method involves the pyrolysis of methane at suitable temperatures over fine powders of certain Mischmetal-based AB3 alloy hydride catalysts,

A. Leela Mohana Reddy; M. M. Shaijumon; S. Ramaprabhu

2006-01-01

33

High-performance hydrogen production and oxidation electrodes with hydrogenase supported on metallic single-wall carbon nanotube networks.  

PubMed

We studied the electrocatalytic activity of an [FeFe]-hydrogenase from Clostridium acetobutylicum (CaH2ase) immobilized on single-wall carbon nanotube (SWNT) networks. SWNT networks were prepared on carbon cloth by ultrasonic spraying of suspensions with predetermined ratios of metallic and semiconducting nanotubes. Current densities for both proton reduction and hydrogen oxidation electrocatalytic activities were at least 1 order of magnitude higher when hydrogenase was immobilized onto SWNT networks with high metallic tube (m-SWNT) content in comparison to hydrogenase supported on networks with low metallic tube content or when SWNTs were absent. We conclude that the increase in electrocatalytic activities in the presence of SWNTs was mainly due to the m-SWNT fraction and can be attributed to (i) substantial increases in the active electrode surface area, and (ii) improved electronic coupling between CaH2ase redox-active sites and the electrode surface. PMID:21384925

Svedruži?, Draženka; Blackburn, Jeffrey L; Tenent, Robert C; Rocha, John-David R; Vinzant, Todd B; Heben, Michael J; King, Paul W

2011-03-08

34

Effect of first row transition metals on the conductivity of semiconducting single-walled carbon nanotube networks  

NASA Astrophysics Data System (ADS)

We demonstrate the ability of first row transition metals to form electrically conducting interconnects between semiconducting single-walled carbon nanotubes (SWNTs) by constructive rehybridization between sidewall benzene rings as a result of the formation of bis-hexahapto-metal-bonds [(?6-SWNT)M(?6-SWNT)], which bridge adjacent SWNTs. Metal deposition on SWNT films enhances the conductivity by three distinct mechanisms: physisorption of gold leads to the formation of a non-interacting gold film and a monotonic conductivity increase; ionic chemisorption of lithium strongly increases the conductivity due to charge transfer to the SWNTs; covalent chemisorption of first row transition metals leads to an abrupt change in conductivity due to formation of (?6-SWNT)M(?6-SWNT) interconnects.

Wang, Feihu; Itkis, Mikhail E.; Bekyarova, Elena B.; Tian, Xiaojuan; Sarkar, Santanu; Pekker, Aron; Kalinina, Irina; Moser, Matthew L.; Haddon, Robert C.

2012-05-01

35

Fast detection of the metallic state of individual single-walled carbon nanotubes using a transient-absorption optical microscope.  

PubMed

In spite of the outstanding properties of single-walled carbon nanotubes (SWNTs), the coexistence of metallic and semiconducting SWNTs as a result of synthesis has hindered their electronic and photonic applications. We demonstrate a pump-probe microscopy method for fast, contact-free mapping of metallicity in individual SWNTs. We employ the phase of transient absorption as a contrast to discriminate metallic and semiconducting SWNTs. Furthermore, we have clarified the phase dependence on the pump or probe wavelengths and the energy structure of SWNTs. Our imaging method holds the potential of serving as a high-speed metallicity-mapping tool to assist the development of SWNT-based nanoelectronics. PMID:21231351

Jung, Yookyung; Slipchenko, Mikhail N; Liu, Chang Hua; Ribbe, Alexander E; Zhong, Zhaohui; Yang, Chen; Cheng, Ji-Xin

2010-11-15

36

Catalytic Routes Towards Single Wall Carbon Nanotubes  

Microsoft Academic Search

Single wall carbon nanotubes (SWCNT) have become a strategic material in the area of nanotechnologies nowadays, and catalytic chemical vapor deposition seems to be the most promising technique in view of an industrial?scale production. However, the selective catalytic production of single wall carbon nanotubes is still a challenge, since catalytic systems performances both in terms of selectivity and activity are

Emmanuel Lamouroux; Philippe Serp; Philippe Kalck

2007-01-01

37

Neat single wall carbon nanotube fiber  

Microsoft Academic Search

Here we report the production of the first ever macroscopic single wall carbon nanotube fibers that consist of only nanotubes without any underlying surfactant or polymer substructure. The single wall carbon nanotube (SWNT) fibers were spun from the dispersion of purified SWNTs with concentrations from 4wt(100spinning techniques. The SWNTs fibers have high alignment and good electrical conductivity.

Hua Fan; Lars Ericson; Virginia Davis; Haiqing Peng; Nicholas Parra-Vasquez; Joseph Sulpizio; Sivarajan Ramesh; Wade Adams; Matteo Pasquali; Howard Schmidz; Robert Hauge; Richard Smalley

2004-01-01

38

Thin-film metal catalyst for the production of multi-wall and single-wall carbon nanotubes  

NASA Astrophysics Data System (ADS)

We present a detailed study of the growth of multiwall and single-wall carbon nanotubes (SWCNTs) by chemical-vapor deposition using a thin-film triple metal (Al/Fe/Mo) catalyst. Using Nanoauger spectroscopy, a full map of the metals in the sample surface is constructed and their evolution followed at different deposition temperatures. During the formation of SWCNTs at high temperatures (~1000 °C), the initial iron layer (~1 nm) is transformed into nanosized particles at the surface. In addition, the Al layer also plays a critical role during the annealing process by being altered into AlxOy particles. These particles act as a suitable underlayer to stabilize the nanosized Fe catalyst for nanotube growth. We also show that it is possible to resolve SWCNTs by mapping the areal intensity of carbon KVV Auger electrons.

Lacerda, R. G.; Teo, K. B. K.; Teh, A. S.; Yang, M. H.; Dalal, S. H.; Jefferson, D. A.; Durrell, J. H.; Rupesinghe, N. L.; Roy, D.; Amaratunga, G. A. J.; Milne, W. I.; Wyczisk, F.; Legagneux, P.; Chhowalla, M.

2004-10-01

39

The effect of the catalyst metals on the thermal-oxidative stability of single-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

In this work, we analyzed the effect of the catalyst metals with various forms on the thermal-oxidative stability of single-walled carbon nanotubes (SWCNTs) by using thermogravimetric analysis (TGA), transmission electron microscopy (TEM), and electronic dispersive X-ray spectroscopy (EDX). The results indicate that the catalyst metal nanoparticles encapsulated inside multi-shelled graphite particles play a main role on destabilizing SWCNTs during their air oxidation. We also compared the thermal stability of SWCNTs in the cloth-like soot and the cotton-like soot produced by arc-discharge. The SWCNTs in the cotton-like soot are of higher thermal-oxidation stability than that in the cloth-like soot due to fewer multi-shelled graphite nanoparticles encapsulating metal nanoparticles.

Wu, Chuxin; Xu, Jiaoxing; Li, Jiaxin; Dong, Guofa; Guan, Lunhui

2009-08-01

40

Transparent Conductive Single-Walled Carbon Nanotube Networks with Precisely Tunable Ratios of Semiconducting and Metallic Nanaotubes  

SciTech Connect

We present a comprehensive study of the optical and electrical properties of transparent conductive films made from precisely tuned ratios of metallic and semiconducting single-wall carbon nanotubes. The conductivity and transparency of the SWNT films are controlled by an interplay between localized and delocalized carriers, as determined by the SWNT electronic structure, tube-tube junctions, and intentional and unintentional redox dopants. The results suggest that the main resistance in the SWNT thin films is the resistance associated with tube-tube junctions. Redox dopants are found to increase the delocalized carrier density and transmission probability through intertube junctions more effectively for semiconductor-enriched films than for metal-enriched films. As a result, redox-doped semiconductor-enriched films are more conductive than either intrinsic or redox-doped metal-enriched films.

Blackburn, J. L.; Barnes, T. M.; Beard, M. C.; Kim, Y.-H.; Tenent, R. C.; McDonald, T. J.; To, B.; Coutts, T. J.; Heben, M. J.

2008-01-01

41

Effects of hydrogen adsorption on single-wall carbon nanotubes: Metallic hydrogen decoration  

Microsoft Academic Search

We show that the electronic and atomic structure of carbon nanotubes undergo dramatic changes with hydrogen chemisorption from first principle calculations. Upon uniform exohydrogenation at half coverage, the cross sections of zigzag nanotubes become literally square or rectangular, and they are metallic with very high density of states at the Fermi level, while other isomers can be insulating. For both

O. Gülseren; T. Yildirim; S. Ciraci

2002-01-01

42

Internal stress induced metallization of single-walled carbon nanotubes in a nanotube/glass conducting composite  

NASA Astrophysics Data System (ADS)

Single-walled carbon nanotubes (SWCNTs) have been incorporated into a (Pb, Zn)—phosphate glass host by a melt-quenching technique. Studies of the optical and electronic properties show that the nanotubes in the composite have suffered conformational deformations and attained a band structure of quasimetallic type, making the composite a good electrical conductor. Possible strains in the nanotubes of the composite such as radial compression, torsion and bending have been considered and their role in modulating the band structures has been analyzed by judging the change in band gap energies (?E) of the deformed SWCNTs using an equation which is based on the ?-electron tight binding model. The effect of ?*-?* hybridization due to the radial compression in generating the metallicity is also discussed. The carrier transport in the composite above room temperature has been shown to be dominated by fluctuation induced tunneling.

Balaji, Sathravada; Debnath, Radhaballabh

2011-10-01

43

Internal stress induced metallization of single-walled carbon nanotubes in a nanotube/glass conducting composite.  

PubMed

Single-walled carbon nanotubes (SWCNTs) have been incorporated into a (Pb, Zn)-phosphate glass host by a melt-quenching technique. Studies of the optical and electronic properties show that the nanotubes in the composite have suffered conformational deformations and attained a band structure of quasimetallic type, making the composite a good electrical conductor. Possible strains in the nanotubes of the composite such as radial compression, torsion and bending have been considered and their role in modulating the band structures has been analyzed by judging the change in band gap energies (?E) of the deformed SWCNTs using an equation which is based on the ?-electron tight binding model. The effect of ?*-?* hybridization due to the radial compression in generating the metallicity is also discussed. The carrier transport in the composite above room temperature has been shown to be dominated by fluctuation induced tunneling. PMID:21926456

Balaji, Sathravada; Debnath, Radhaballabh

2011-09-16

44

Macroscopic Neat Single Wall Carbon Nanotube Fibers  

Microsoft Academic Search

Measured and predicted properties of single wall carbon nanotubes (SWNT) suggest that neat SWNT fibers will exhibit a variety of exceptional properties. Macroscopic fibers composed entirely of single wall carbon nanotubes (SWNT) have been successfully created. HiPco SWNT were dispersed in strong acids at high concentrations (4-10wt%) and extruded using conventional fiber spinning methods. The fibers exhibit remarkable internal alignment,

Lars M. Ericson; Sivarajan Ramesh; Rajesh Saini; Virginia A. Davis; Carter Kittrell; Michael J. Casavant; Matteo Pasquali; Robert H. Hauge; Richard E. Smalley; Alan Dalton; Ray H. Baughman; John E. Fischer

2002-01-01

45

Single-Walled Carbon Nanotube Transparent Electrodes  

NASA Astrophysics Data System (ADS)

Transparent conducting electrodes made from thin-film networks of single-walled carbon nanotubes (SWCNTs) are an alternative to transparent conducting oxides in many optoelectronic device applications. However, we have shown the electrical conductivity of SWCNT electrodes is limited by energy barriers at the nanotube-nanotube interfaces throughout the thin-film network [Barnes, et al., ACS Nano 2, 1968 (2008)]. We investigate various fabrication and treatment conditions to improve the electrical and optical properties of these SWCNT films. One potential pathway to improvement is to change the distribution of metallic-to-semiconducting tube types within the SWCNT network. We report the thorough characterization of SWCNT network electrodes with highly enriched metallic or semiconducting tube content through optical transmission and electrical transport measurements, as well as their performance in both organic and inorganic thin-film photovoltaic devices.

Bergeson, Jeremy D.; Blackburn, Jeffrey L.; Brown, Patrick R.; Larsen, Brian A.; Reese, Matthew O.; Barnes, Teresa M.

2010-03-01

46

Electronic specific heat of single-walled carbon nanotubes  

Microsoft Academic Search

The electronic structure of single-walled carbon nanotubes is calculated by the tight-binding model. A single-walled carbon nanotube could drastically change from a metal to a semiconductor or vice versa during the variation of magnetic flux. The low-temperature electronic specific heat thus exhibits the rich temperature and magnetic-flux dependence. There are four kinds of temperature dependence in the presence of the

Ming-Fa Lin; Kenneth Wen-Kai Shung; Der-San Chuu

1996-01-01

47

Preferential growth of short aligned, metallic-rich single-walled carbon nanotubes from perpendicular layered double hydroxide film  

NASA Astrophysics Data System (ADS)

Direct bulk growth of single-walled carbon nanotubes (SWCNTs) with required properties, such as diameter, length, and chirality, is the first step to realize their advanced applications in electrical and optical devices, transparent conductive films, and high-performance field-effect transistors. Preferential growth of short aligned, metallic-rich SWCNTs is a great challenge to the carbon nanotube community. We report the bulk preferential growth of short aligned SWCNTs from perpendicular Mo-containing FeMgAl layered double hydroxide (LDH) film by a facile thermal chemical vapor deposition with CH4 as carbon source. The growth of the short aligned SWCNTs showed a decreased growth velocity with an initial value of 1.9 nm s-1. Such a low growth velocity made it possible to get aligned SWCNTs shorter than 1 ?m with a growth duration less than 15 min. Raman spectra with different excitation wavelengths indicated that the as-grown short aligned SWCNTs showed high selectivity of metallic SWCNTs. Various kinds of materials, such as mica, quartz, Cu foil, and carbon fiber, can serve as the substrates for the growth of perpendicular FeMoMgAl LDH films and also the growth of the short aligned SWCNTs subsequently. These findings highlight the easy route for bulk preferential growth of aligned metallic-rich SWCNTs with well defined length for further bulk characterization and applications.Direct bulk growth of single-walled carbon nanotubes (SWCNTs) with required properties, such as diameter, length, and chirality, is the first step to realize their advanced applications in electrical and optical devices, transparent conductive films, and high-performance field-effect transistors. Preferential growth of short aligned, metallic-rich SWCNTs is a great challenge to the carbon nanotube community. We report the bulk preferential growth of short aligned SWCNTs from perpendicular Mo-containing FeMgAl layered double hydroxide (LDH) film by a facile thermal chemical vapor deposition with CH4 as carbon source. The growth of the short aligned SWCNTs showed a decreased growth velocity with an initial value of 1.9 nm s-1. Such a low growth velocity made it possible to get aligned SWCNTs shorter than 1 ?m with a growth duration less than 15 min. Raman spectra with different excitation wavelengths indicated that the as-grown short aligned SWCNTs showed high selectivity of metallic SWCNTs. Various kinds of materials, such as mica, quartz, Cu foil, and carbon fiber, can serve as the substrates for the growth of perpendicular FeMoMgAl LDH films and also the growth of the short aligned SWCNTs subsequently. These findings highlight the easy route for bulk preferential growth of aligned metallic-rich SWCNTs with well defined length for further bulk characterization and applications. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr00043a

Zhao, Meng-Qiang; Tian, Gui-Li; Zhang, Qiang; Huang, Jia-Qi; Nie, Jing-Qi; Wei, Fei

2012-03-01

48

Thermal stability of metallic single-walled carbon nanotubes: an O(N) tight-binding molecular dynamics simulation study  

NASA Astrophysics Data System (ADS)

Order(N) tight-binding molecular dynamics (TBMD) simulations are performed to investigate the thermal stability of (10,10) metallic single-walled carbon nanotubes (SWCNTs). Periodic boundary conditions (PBCs) are applied in the axial direction. The velocity Verlet algorithm along with the canonical ensemble molecular dynamics (NVT) is used to simulate the tubes at the targeted temperatures. The effects of slow and rapid temperature increases on the physical characteristics, structural stability and the energetics of the tube are investigated and compared. Simulations are carried out starting from room temperature and the temperature is raised in steps of 300 K. The stability of the simulated metallic SWCNT is examined at each step before it is heated to higher temperatures. The first indication of structural deformation is observed at 600 K. For higher heat treatments the deformations are more pronounced and the bond-breaking temperature is reached around 2500 K. Gradual (slow) heating and thermal equilibrium (fast heating) methods give the value of radial thermal expansion coefficient in the temperature range between 300 and 600 K as 0.31 × 10-5 and 0.089 × 10-5 K-1, respectively. After 600 K, both methods give the same value of 0.089 × 10-5 K-1. The ratio of the total energy per atom with respect to temperature is found to be 3 × 10-4 eV K-1.

Dereli, G.; Süngü, B.; Özdogan, C.

2007-06-01

49

Experimental and theoretical comparison of gas desorption energies on metallic and semiconducting single-walled carbon nanotubes.  

PubMed

Single-walled carbon nanotubes (SWNTs) exhibit high surface areas and precisely defined pores, making them potentially useful materials for gas adsorption and purification. A thorough understanding of the interactions between adsorbates and SWNTs is therefore critical to predicting adsorption isotherms and selectivities. Metallic (M-) and semiconducting (S-) SWNTs have extremely different polarizabilities that might be expected to significantly affect the adsorption energies of molecules. We experimentally and theoretically show that this expectation is contradicted, for both a long chain molecule (n-heptane) and atoms (Ar, Kr, and Xe). Temperature-programmed desorption experiments are combined with van der Waals corrected density functional theory, examining adsorption on interior and exterior sites of the SWNTs. Our calculations show a clear dependence of the adsorption energy on nanotube diameter but not on whether the tubes are conducting or insulating. We find no significant experimental or theoretical difference in adsorption energies for molecules adsorbed on M- and S-SWNTs having the same diameter. Hence, we conclude that the differences in polarizabilities between M- and S-SWNTs have a negligible influence on gas adsorption for spherical molecules as well as for highly anisotropic molecules such as n-heptane. We expect this conclusion to apply to all types of adsorbed molecules where van der Waals interactions govern the molecular interaction with the SWNT. PMID:23627526

Mandeltort, Lynn; Chen, De-Li; Saidi, Wissam A; Johnson, J Karl; Cole, Milton W; Yates, John T

2013-05-13

50

Formylation of single-walled carbon nanotubes  

Microsoft Academic Search

Formyl or aldehyde groups are transferred to the surface of single-walled carbon nanotubes (SWCNTs) by reaction of reduced carbon nanotubes with N-formylpiperidine. This could open the way for more versatile chemical modification reactions of carbon nanotubes than is currently possible using functionalization methods reported to date. The formylated SWCNTs were characterized by thermogravimetric analysis–mass spectrometry and Raman, UV–vis–NIR and FTIR

Mustafa K. Bayazit; Anil Suri; Karl S. Coleman

2010-01-01

51

The Electronic Specific Heat of single-walled Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

The electronic structure of single-walled carbon nanotubes is calculated by the tight-binding model. A single-walled carbon nanotube could drastically change from a metal (semiconductor) to a semiconductor (metal) during the variation of magnetic flux. The low-temperature electronic specific heat thus exhibits the rich temperature and magnetic-flux dependence. There are four kinds of temperature dependence in the presence of the magnetic field, mainly due to the interaction between spin and magnetic field. Furthermore, the flux-dependent specific heat exhibits the pronounced oscillatory behavior including asymmetric two-peak structures. These structures strongly depends on the characteristics of the subbands nearest the Fermi level.

Lin, Ming-Fa; Shung, Kenneth Wen-Kai; Chuu, Der-San

1996-03-01

52

Carboxymethylcellulose/single walled carbon nanotube complexes.  

PubMed

In this work, Carboxymethylcellulose/single walled carbon nanotube hybrids are prepared. Our goal is to use the non-covalent association of an anionic polysaccharide and single walled carbon nanotubes to prepare a biocompatible complex which preserves the intrinsic properties of the nanotubes. The hybrids are characterized by Raman scattering, Emission spectroscopy and Atomic Force Microscopy. A comparison is made with sodium dodecyl benzene sulfonate dispersed nanotubes. We show that carboxymethylcellulose forms an apparently non-helicoidal superstructure with carbon nanotubes which leads to their individualization. Emission and Raman spectroscopies suggest that the interaction occurs preferentially with semiconducting nanotubes. Further sugar chemistry may open different functionalization opportunities that will contribute to the design of biosensors and open this field of applications. PMID:19908512

Riou, I; Bertoncini, P; Bizot, H; Mevellec, J Y; Buléon, A; Chauvet, O

2009-10-01

53

Electronic structure of tubular aromatic molecules derived from the metallic (5,5) armchair single wall carbon nanotube.  

PubMed

All-electron static and time-dependent DFT electronic calculations, with complete geometrical optimization, are performed on tubular molecules up to C(210)H(20) that are finite sections of the (5,5) metallic single wall carbon nanotube with hydrogen termination at the open ends. We find pronounced C-C bond reconstruction at the tube ends; this initiates bond alternation that propagates into the tube centers. For the especially low band gap molecules C(120)H(20), C(150)H(20), and C(180)H(20), alternation increases, and a second nearly isoenergic structural isomer of different alternation is found. A small residual C-C bond alternation and band gap may be present in the infinite tube. The van Hove band gap forms quickly with length, while the metallic Fermi point (at the crossing of linear bands) forms very slowly with length. There are no end-localized states at energies near the Fermi energy. The HOMO-LUMO gap and the lowest singlet excited state, whose energies show a periodicity with length as previously calculated, are optically forbidden. However, each molecule shows an intense visible "charge transfer" transition, not present in the infinite tube, whose energy varies smoothly with length; this transition should be an identifying signature for these molecules. The static axial polarizability per unit length increases rapidly with N as the "charge transfer" transition moves into the infrared; this indicates increasing metallic character. However, the ionization potential, electron affinity, chemical hardness, and relative energetic stability all show the length periodicity seen in the HOMO-LUMO gap, in contrast to the optical "charge transfer" transition and the static axial polarizability. These periodicities, due to a one-dimensional quantum size effect as originally modeled by Coulson in 1938, nevertheless cancel in the calculated Fermi energy, which varies smoothly toward a predicted bulk work function near 3.9 eV. A detailed study of C(190)H(20) with up to eight extra electrons or holes shows the total energy is closely fit by a simple classical charging model, as is commonly applied to metallic clusters. PMID:15025489

Zhou, Zhiyong; Steigerwald, Michael; Hybertsen, Mark; Brus, Louis; Friesner, Richard A

2004-03-24

54

Molecular discriminators using single wall carbon nanotubes  

NASA Astrophysics Data System (ADS)

The interaction between single wall carbon nanotubes (SWNTs) and amphiphilic molecules has been studied in a solid phase. SWNTs are allowed to interact with different amphiphilic probes (e.g. lipids) in a narrow capillary interface. Contact between strong hydrophobic and amphiphilic interfaces leads to a molecular restructuring of the lipids at the interface. The geometry of the diffusion front and the rate and the extent of diffusion of the interface are dependent on the structure of the lipid at the interface. Lecithin having a linear tail showed greater mobility of the interface as compared to a branched tail lipid like dipalmitoyl phosphatidylcholine, indicating the hydrophobic interaction between single wall carbon nanotube core and the hydrophobic tail of the lipid. Solid phase interactions between SWNT and lipids can thus become a very simple but efficient means of discriminating amphiphilic molecules in general and lipids in particular.

Bhattacharyya, Tamoghna; Dasgupta, Anjan Kr; Ranjan Ray, Nihar; Sarkar, Sabyasachi

2012-09-01

55

Purification of single-wall carbon nanotubes  

Microsoft Academic Search

With Y–Ni alloy and CaC2–Ni as catalyst, large-scale single-wall carbon nanotubes (SWCNTs) were produced by d.c. arc-discharge method. The yield of SWCNTs and the composition of the raw-soot was quantified with thermogravimetric analysis (TGA). The burning temperature of SWCNTs in air was also determined. On these bases, 350°C was chosen for the first step purification of SWCNTs. Combining with the

Zujin Shi; Yongfu Lian; Fuhui Liao; Xihuang Zhou; Zhennan Gu; Yaogang Zhang; Sumio Iijima

1999-01-01

56

Antiseptic single wall carbon nanotube bandages  

Microsoft Academic Search

Single wall carbon nanotubes (SWCNTs) are coated with polyvinylpyrrolidone-iodine (povidone-iodine or PVPI) in water. This solution of SWCNT and PVPI is deposited as a composite film, composed of individual and bundled SWCNTs with a PVPI coating. This material acts as a conductive nanotextured bandage with high flexibility and self contained slow-release antiseptic iodine. Antibacterial properties were tested on Escherichia coli,

T. J. Simmons; S.-H. Lee; T.-J. Park; D. P. Hashim; P. M. Ajayan; R. J. Linhardt

2009-01-01

57

Direct synthesis of single-walled carbon nanotubes bridging metal electrodes by laser-assisted chemical vapor deposition  

NASA Astrophysics Data System (ADS)

Direct synthesis of single-walled carbon nanotubes (SWNTs) bridging prepatterned Mo electrodes has been achieved using laser-assisted chemical vapor deposition (LCVD). The synthesized SWNTs are found predominantly semiconducting. By controlling the spot size of the focused laser beam, synthesis of SWNTs can be achieved in a localized manner, which is governed by the thermal and optical properties of materials as well as the laser parameters. The synthesis process is fast and can be achieved in both far- and near-infrared laser wavelength regions. LCVD method provides a potential approach to in situ remove SWNTs with specific chiralities during the growth.

Shi, J.; Lu, Y. F.; Yi, K. J.; Lin, Y. S.; Liou, S. H.; Hou, J. B.; Wang, X. W.

2006-08-01

58

Stable geometries and magnetic properties of single-walled carbon nanotubes doped with 3d transition metals: A first-principles study  

Microsoft Academic Search

The interaction of 3d transition metal atoms and dimers with a single-walled armchair carbon nanotube has been investigated by first-principles density functional calculations. For Fe-, Co-, and Ni-doped (4,4) nanotubes, outside adsorption sites are the most favorable. The interactions are largely ferromagnetic for Fe and Co, with the local magnetic moments of the dimers being similar to the free dimers.

Yosuke Yagi; Tina M. Briere; Marcel H. Sluiter; Vijay Kumar; Amir A. Farajian; Yoshiyuki Kawazoe

2004-01-01

59

A simple purification for single-walled carbon nanotubes  

Microsoft Academic Search

A simple, effective and non-destructive purification process for single-walled carbon nanotubes synthesized by arc discharge has been demonstrated in this paper. The by-products, amorphous carbon, multi-walled graphite and metallic catalyst, were eliminated successfully by a combination of ultrasonication in the presence of surfactant and gas oxidation. The oxidation in oxygen is advantageous against wet chemical methods because it is easily

Jinyong Li; Yafei Zhang

2005-01-01

60

Magnetic properties of strained single-walled carbon nanotubes  

Microsoft Academic Search

Strong effects of uniaxial and torsional strains on the magnetic properties of single-walled carbon nanotubes have been investigated by tight binding calculations and the Green function analyses. The strain-induced peaks of susceptibility are found in the carbon nanotubes, and paramagnetic-diamagnetic transition takes place at certain strains. The critical magnetic flux for semiconductor-metal transition changes linearly with strains depending on the

Zhuhua Zhang; Wanlin Guo

2007-01-01

61

Electrical properties of long suspended single-wall carbon nanotubes  

Microsoft Academic Search

Suspended single-wall carbon nanotubes are grown on top of pre-deposited metal electrodes. This configuration allows investigation of the electrical properties of suspended nanotubes up to 10 microns long. Previous experiments have been limited to nanotubes less than 1 micron. Semi-conducting and metallic nanotubes are investigated at low temperatures and with a back gate. Because of their suspended nature these nanotubes

Nathan Franklin; Tom Tombler; Hongjie Dai

2002-01-01

62

Transport properties of single wall carbon nanotubes  

NASA Astrophysics Data System (ADS)

In this thesis, we study the properties of macroscopic samples of single walled carbon nanotubes (SWNT) in the form of buckypapers and fibers, and how these properties are affected by doping, alignment and C60 filling. A metal-insulator (MI) transition in macroscopic SWNT conductors is revealed by systematic measurements of resistivity, rho(T), and transverse magnetoresistance, MR(B), as a function of p-type redox doping. In the insulating regime, the rho( T) can be described by variable-range hopping (VRH) mechanism. The MR(B) and rho(T) of strongly doped samples are best described by a weak localization (WL) model. The 1D character of the electronic and phonon spectra becomes apparent in the thermopower (TEP) of strongly doped samples. In contrast to weakly doped samples, TEP is small at the lowest temperatures, and then increases at a characteristic temperature which depends on the position of the Fermi energy. We attribute this unusual behavior to 1D phonon drag, in which the electron-phonon interaction is restricted to phonons with the appropriate wave-vector. This idea is supported by a model calculation in which the low T behavior of phonon drag is specifically related to the one-dimensional character of the electronic spectrum. TEP data are correlated with optical reflectivity, Raman spectroscopy, mass loss and resistivity measurements. We performed the careful dedoping of H2SO4 doped samples and in situ measurements of the temperature dependence of TEP. It is found that the effect of H2SO4 doping is to change the Fermi energy and not to introduce new features into DOS of SWNTs. A model is developed which can explain some of the features observed in the diffusion TEP. Filling SWNTs with C60 molecules does not have a considerable effect on p and TEP of macroscopic samples and only very weak effect on heat capacity and thermal conductivity is expected. A possibility of observing cluster dynamics using diffraction methods is discussed. We show that the conduction mechanism in bulk SWNT samples is not affected by a partial nanotube alignment. The effect of alignment on rho can be described by a proportionality factor, which depends on the number of rope-rope contacts along the most probable conduction path.

Vavro, Juraj

63

Growth of single-walled carbon nanotubes with large chiral angles on rhodium nanoparticles  

NASA Astrophysics Data System (ADS)

Single-walled carbon nanotubes (SWNTs) grown on rhodium (Rh) nanoparticles were demonstrated to have large chiral angles and a preference for metallic tubes.Single-walled carbon nanotubes (SWNTs) grown on rhodium (Rh) nanoparticles were demonstrated to have large chiral angles and a preference for metallic tubes. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr03259k

He, Maoshuai; Jiang, Hua; Lehtonen, Juha; Kauppinen, Esko I.

2013-10-01

64

Fluidic patch antenna based on liquid metal alloy/single-wall carbon-nanotubes operating at the S-band frequency  

NASA Astrophysics Data System (ADS)

This letter describes the fabrication and characterization of a fluidic patch antenna operating at the S-band frequency (4 GHz). The antenna prototype is composed of a nanocomposite material made by a liquid metal alloy (eutectic gallium indium) blended with single-wall carbon-nanotube (SWNTs). The nanocomposite is then enclosed in a polymeric substrate by employing the UV-assisted direct-writing technology. The fluidic antennas specimens feature excellent performances, in perfect agreement with simulations, showing an increase in the electrical conductivity and reflection coefficient with respect to the SWNTs concentration. The effect of the SWNTs on the long-term stability of antenna's mechanical properties is also demonstrated.

Aïssa, B.; Nedil, M.; Habib, M. A.; Haddad, E.; Jamroz, W.; Therriault, D.; Coulibaly, Y.; Rosei, F.

2013-08-01

65

Is there a Difference in Van Der Waals Interactions between Rare Gas Atoms Adsorbed on Metallic and Semiconducting Single-Walled Carbon Nanotubes?  

NASA Astrophysics Data System (ADS)

The differences in the polarizabilities of metallic (M) and semiconducting (S) single-walled carbon nanotubes (SWNTs) might give rise to differences in adsorption potentials. We show from experiments and van der Waals—corrected density functional theory that the binding energies of Xe adsorbed on M- and S-SWNTs are nearly identical. Temperature programed desorption experiments of Xe on purified M- and S-SWNTs give similar peak temperatures, indicating that desorption kinetics and binding energies are independent of the type of SWNT. Binding energies computed from vdW-corrected density functional theory are in good agreement with experiments.

Chen, De-Li; Mandeltort, Lynn; Saidi, Wissam A.; Yates, John T., Jr.; Cole, Milton W.; Johnson, J. Karl

2013-03-01

66

Electronic specific heat of single-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

The electronic structure of single-walled carbon nanotubes is calculated by the tight-binding model. A single-walled carbon nanotube could drastically change from a metal to a semiconductor or vice versa during the variation of magnetic flux. The low-temperature electronic specific heat thus exhibits the rich temperature and magnetic-flux dependence. There are four kinds of temperature dependence in the presence of the magnetic field, mainly due to the interaction between spin and magnetic field. Moreover, the magnetic-flux-dependent specific heat exhibits the pronounced oscillatory behavior including asymmetric two-peak structures. These structures strongly depend on the characteristics of the subbands nearest the Fermi level.

Lin, M. F.; Shung, Kenneth W.-K.

1996-07-01

67

Formylation of single-walled carbon nanotubes.  

PubMed

We report an improved, elegant method for the covalent formylation of single-wall carbon nanotubes (SWNTs) via formyl transfer from N-formylpiperidine, which could potentially open the gateway for more versatile chemical modification of carbon nanotube (CNT) walls than is possible via other reported functionalisation methods. The formylation reaction does not inflict damage upon the pristine CNT structure, unlike the currently commonly used carboxylation route, and involves much fewer steps, and takes considerably less time, than most other reported routes. The modified SWNTs have been characterised by Raman spectroscopy, ultraviolet-visible-near infrared (UV-vis-NIR) spectroscopy and "covalent tagging" with derivatising groups followed by thermogravimetric analysis-mass spectroscopy (TGA-MS). UV-vis-NIR spectroscopy shows that there is only limited disruption of the intrinsic electronic structure of the SWNTs. This is confirmed from estimates of the extent of functionalisation from TGA-MS, which suggest that it may be as low as 2 atomic per cent. PMID:22755144

Suri, Anil; Coleman, Karl S

2012-03-01

68

A performance analysis for single-walled metallic Carbon Nanotubes as global and intermediate on-chip interconnects  

Microsoft Academic Search

This paper analyzes several delay estimates for metallic carbon nanotubes (CNT) as interconnects of very large scale integrated (VLSI) chips. A study of the 2005 edition of the international technology roadmap (ITRS) [1] for global\\/intermediate interconnects is presented to highlight the significant issues encountered with the projected performance of copper\\/aluminum interconnects till 2020. Then a worst case performance analysis of

Hamidreza Hashempour; Fabrizio Lombardi

2007-01-01

69

TiO2 composing with pristine, metallic or semiconducting single-walled carbon nanotubes: which gives the best performance for a dye-sensitized solar cell.  

PubMed

Different types of single-walled carbon nanotubes (SWCNTs), pristine (p-), metallic (m-) and semiconducting (s-) are incorporated into TiO(2) photoanodes to improve the dye-sensitized solar-cell (DSSC) performance and their effects on the device performance are further investigated. Although all three types of SWCNTs are found to have comparable structural morphologies and a reduced charge transport resistivity for the photoanodes, only the semiconducting one was able to suppress charge-recombination events, resulting in even greater improvement of DSSC performances. This is very likely to be ascribed to the higher energy barrier of s-SWCNTs compared to both m- and p-SWCNTs to block the back flowing of dye-injected electrons for I(3)(-) reduction in the charge recombination process. PMID:22674658

Guai, Guan Hong; Li, Yao; Ng, Chee Mang; Li, Chang Ming; Chan-Park, Mary B

2012-06-06

70

Thermionic Emission of Single-Wall Carbon Nanotubes Measured.  

National Technical Information Service (NTIS)

Researchers at the NASA Glenn Research Center, in collaboration with the Rochester Institute of Technology, have investigated the thermionic properties of high-purity, single-wall carbon nanotubes (SWNTs) for use as electron-emitting electrodes. Carbon na...

G. A. Landis I. L. Krainsky S. G. Bailey J. M. Elich B. J. Landi T. Gennett R. P. Raffaelle

2004-01-01

71

Catalytic activity toward oxygen reduction of transition metal porphyrins covalently linked to single-walled carbon nanotubes: A density functional study  

NASA Astrophysics Data System (ADS)

The interaction of molecular oxygen with the metal center of transition metal porphyrins (MP, with M = Mn, Fe, Co, and Ni) covalently linked to single-walled carbon nanotubes (CNTs) are addressed by density functional theory calculations. Two geometries for the CNT sidewall functionalization with porphyrin radicals are proposed, considering sp2 and sp3 chemical bonds. By computing the stability and electronic properties of the CNT-MP complexes, and the interaction of the O2 molecule with the metal center, we investigate their catalytic activity toward the oxygen reduction reaction (ORR). According to our results, CNT-MnP, CNT-CoP, and CNT-FeP linked by sp2 covalent bonds are highly stable, preserving the CNT metallic character. We also find a significant O-O bond weakening after the oxygen adsorption on the porphyrin metal center, showing favorable conditions toward ORR. These results support experimental evidences of ORR activity in CNT-based transition metal-N4 centers.

Orellana, Walter

2011-10-01

72

Determination of the metallic/semiconducting ratio in bulk single-wall carbon nanotube samples by cobalt porphyrin probe electron paramagnetic resonance spectroscopy.  

PubMed

A simple and quantitative, self-calibrating spectroscopic technique for the determination of the ratio of metallic to semiconducting single-wall carbon nanotubes (SWCNTs) in a bulk sample is presented. The technique is based on the measurement of the electron paramagnetic resonance (EPR) spectrum of the SWCNT sample to which cobalt(II)octaethylporphyrin (CoOEP) probe molecules have been added. This yields signals from both CoOEP molecules on metallic and on semiconducting tubes, which are easily distinguished and accurately characterized in this work. By applying this technique to a variety of SWCNT samples produced by different synthesis methods, it is shown that these signals for metallic and semiconducting tubes are independent of other factors such as tube length, defect density, and diameter, allowing the intensities of both signals for arbitrary samples to be retrieved by a straightforward least-squares regression. The technique is self-calibrating in that the EPR intensity can be directly related to the number of spins (number of CoOEP probe molecules), and as the adsorption of the CoOEP molecules is itself found to be unbiased toward metallic or semiconducting tubes, the measured intensities can be directly related to the mass percentage of metallic and semiconducting tubes in the bulk SWCNT sample. With the use of this method it was found that for some samples the metallic/semiconducting ratios strongly differed from the usual 1:2 ratio. PMID:20958073

Cambré, Sofie; Wenseleers, Wim; Goovaerts, Etienne; Resasco, Daniel E

2010-10-19

73

Assembling techniques for micellar dispersed carbon single-walled nanotubes  

NASA Astrophysics Data System (ADS)

Surfactant-stabilised aqueous dispersions of carbon single-walled nanotubes (SWNTs) provide attractive possibilities for different types of assembling processes. The adsorption behaviour of chromatographically purified, micellar suspended SWNTs on silica substrates and metal electrodes is presented. Chemical modifications of the substrate surface allow to control the adsorption kinetics and the fraction between adsorbed individual SWNTs and bundles of SWNTs. Tube alignment occurs presumably due to flow effects upon removal of the surfactant. As a second assembling technique, we describe the preparation of Langmuir-Blodgett films consisting of SWNTs embedded in a surfactant matrix.

Burghard, M.; Muster, J.; Duesberg, G.; Philipp, G.; Krstic, V.; Roth, S.

1998-08-01

74

Electronic Durability of Flexible Transparent Films from Type-Specific Single-Wall Carbon Nanotubes.  

National Technical Information Service (NTIS)

The coupling between mechanical flexibility and electronic performance is evaluated for thin films of metallic and semiconducting single-wall carbon nanotubes (SWCNTs) deposited on compliant supports. Percolated networks of type-purified SWCNTs are assemb...

A. K. Bernhardt G. R. S. Iyer J. M. Harris J. Y. Huh S. D. Hudson

2011-01-01

75

Vertical Alignment of Single-Walled Carbon Nanotubes on Nanostructure Fabricated by Atomic Force Microscope.  

National Technical Information Service (NTIS)

This project focused on the behavior of single-wall carbon nanotubes (SWCNTs) in the electrophoresis cells and aligned growth of SWCNTs by thermal chemical vapor deposition on selectively deposited metallic nanoparticles. Field emission characteristics of...

H. Lee

2007-01-01

76

Simplified synthesis of single-walled carbon nanotubes from a botanical hydrocarbon: Turpentine oil  

Microsoft Academic Search

Turpentine oil (C10H16), a botanical hydrocarbon, has been found to be an effective precursor of single-walled carbon nanotubes (SWNTs).Single-walled carbon nanotubes were prepared by catalytic decomposition of turpentine oil over well-dispersed metal particles supported on high silica Y-type zeolite at 850°C by spray pyrolysis method with a reaction time 25min. The concentration of the each metal species (Co and Fe)

Pradip Ghosh; T. Soga; Rakesh A. Afre; T. Jimbo

2008-01-01

77

Electrical Transport through Single-Wall Carbon Nanotubes in Perpendicular Oriented Magnetic Fields  

Microsoft Academic Search

Individual thin Single-Walled Carbon Nanotubes bundles were connected to noble metal leads with low contact resistance between tube and metal. Electrical transport measurements on these devices are presented, performed at temperatures of about 50 mK in a magnetic field perpendicular to the Single-Walled Carbon Nanotubes symmetry axis. In these measurements we have investigated the dependence of the electrical transport on

V. Krstic; J. Weis; S. Roth

2002-01-01

78

Single wall carbon nanotubes: Separation and applications to biosensors  

NASA Astrophysics Data System (ADS)

Single wall carbon nanotubes uniquely exhibit one-dimensional quantum confined properties by being either semiconducting (sem-) or metallic (met-) depending on their atomic arrangements. The stochastic nature of SWNT growth renders met-:sem- ratio being 1:2 and diameter range being distributed in 0.4-2nm with a close-packed bundle configuration. For many high-performance devices using SWNTs, acquiring well-separated and/or isolated single-diameter, metallicity and/or chirality nanotubes is greatly in demand. Recently, the bulk separation and/or enrichment of single wall carbon nanotubes (SWNTs) according to type (or otherwise termed "metallicity") and diameter (dt) has become possible. This thesis presents a route to probe mechanisms in diameter and metallicity dependent separation of SWNTs. A systematic analysis tool, that enables the quantitative examination of resonance Raman spectra, is established from nanotube samples that have been separated according to metallicity and d t via an octadecylamine mediated protocol. This protocol uses the relative changes in the integrated intensities of the radial-breathing mode region for the quantitative evaluation. By further establishing the physicochemical properties of charge-stabilized SWNT dispersions in polar aprotic media (i.e. N,N-dimethylformide) a more detailed description of the underlying separation mechanism is given. Here, I use resonance Raman spectroscopy (RRS) as a tool to probe SWNT redox chemistry. The Gibbs free energy, modeled by calculating the charge-loss from the (n,m)-dependent integrated density of states across the corresponding jump in the redox potential, is utilized to support the separation mechanism. Additionally, the evaluation of SWNT forest platforms for amperometric protein immunoassays is presented. Horseradish peroxidase is used as the label and the sensing signals are acquired from electrochemical reduction of hydrogen peroxide. Specific studies on human serum albumin and prostate specific antigen detection are explained. Signal amplification strategies are introduced by using redox mediator, enzyme, and enzyme-decorated carbon nanotubes.

Kim, Sang Nyon

79

High Yield Methods for Cutting Single-Walled Carbon Nanotubes.  

National Technical Information Service (NTIS)

Methods for cutting single-walled carbon nanotubes (SWNTs) to controlled lengths for material, biological and electronic applications are being developed. The research aims at establishing scalable cutting processes for preparing high quality short SWNTs ...

H. K. Schmidt K. J. Ziegler U. Rauwald Z. Chen Z. Gu

2008-01-01

80

40 CFR 721.10156 - Single-walled carbon nanotubes (generic).  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Single-walled carbon nanotubes (generic). 721.10156...Substances § 721.10156 Single-walled carbon nanotubes (generic). (a) Chemical...identified generically as single-walled carbon nanotubes (PMN...

2013-07-01

81

Room temperature growth of single wall carbon nanotube Y-branches  

NASA Astrophysics Data System (ADS)

The growth of carbon nanotubes from fullerene fragments produced by catalytic decomposition in the presence of transition metals at about 450°C was investigated. Multi wall and single wall nanotubes are grown by vapor deposition on highly oriented pyrolytic graphite (HOPG) at room temperature. No further purification or manipulation is necessary for investigations by scanning tunneling microscopy. The templating effect of the substrate is assumed to be an important growth condition. No tubes were found on Au(111) or mica surfaces. Individual tubes and raft like structures of multiwalled tubes and bundles of single walled tubes were found on HOPG. Several cases of Y-branching of single wall carbon nanotubes were observed. .

Ehlich, R.; Biró, L. P.; Stanciu, C.; Horváth, Z. E.; Gyulai, J.

2001-11-01

82

Growth velocity and direct length-sorted growth of short single-walled carbon nanotubes by a metal-catalyst-free chemical vapor deposition process.  

PubMed

We report on the observation of a very low growth velocity of single-walled carbon nanotubes (SWNTs) and consequently the direct length-sorted growth and patterned growth of SWNTs by using a metal-catalyst-free chemical vapor deposition (CVD) process proposed recently by our group, in which SiO(2) serves as catalyst. We found that the growth velocity of the SWNTs from SiO(2) catalyst is only 8.3 nm/s, which is about 300 times slower than that of the commonly used iron group catalysts (Co as a counterpart catalyst in this study). Such a slow growth velocity renders direct length-sorted growth of SWNTs, especially for short SWNTs with hundreds of nanometers in length. By simply adjusting the growth duration, SWNTs with average lengths of 149, 342, and 483 nm were selectively obtained and SWNTs as short as approximately 20 nm in length can be grown directly. Moreover, comparative studies indicate that the SiO(2) catalyst possesses a much longer catalytic active time, showing sharp contrast with the commonly used Co catalyst which quickly loses its catalytic activity. Taking advantage of the very slow growth velocity of the SiO(2) catalyst, patterned growth of SWNT networks confined in a narrow region of <5 microm was also achieved. The short SWNTs may show intriguing physics owing to their finite length effect and are attractive for various practical applications. PMID:19856907

Liu, Bilu; Ren, Wencai; Liu, Chang; Sun, Cheng-Hua; Gao, Libo; Li, Shisheng; Jiang, Chuanbin; Cheng, Hui-Ming

2009-11-24

83

Optical properties of intercalated single-wall carbon nanotubes  

NASA Astrophysics Data System (ADS)

The optical properties of alkali-metal intercalated single-wall carbon nanotubes have been investigated using high-resolution electron energy-loss spectroscopy in transmission. The modulation of the filling of the van Hove singularities in the electronic density of states is reflected by the intensity variations of the optical excitations and the appearance of a charge carrier plasmon. The low-energy loss function can be described using a Drude-Lorentz model. Within this model, the optical conductivity at zero frequency ?0 of Na, K, Rb, and Cs intercalated SWCNT samples were determined and give similar values for maximum intercalation. This model has also been used to derive the dielectric background and the effective (optical) charge carrier mass of the intercalated SWCNTs which is found to be two to three times bigger than in the corresponding graphite intercalation compounds.

Liu, X.; Pichler, T.; Knupfer, M.; Fink, J.

2003-10-01

84

Diameter-dependent solubility of single-walled carbon nanotubes.  

PubMed

We study the solubility and dispersibility of as-produced and purified HiPco single-walled carbon nanotubes (SWNTs). Variation in specific operating conditions of the HiPco process are found to lead to significant differences in the respective SWNT solubilities in oleum and surfactant suspensions. The diameter distributions of SWNTs dispersed in surfactant solutions are batch-dependent, as evidenced by luminescence and Raman spectroscopies, but are identical for metallic and semiconducting SWNTs within a batch. We thus find that small diameter SWNTs disperse at higher concentration in aqueous surfactants and dissolve at higher concentration in oleum than do large-diameter SWNTs. These results highlight the importance of controlling SWNT synthesis methods in order to optimize processes dependent on solubility, including macroscopic processing such as fiber spinning, material reinforcement, and films production, as well as for fundamental research in type selective chemistry, optoelectronics, and nanophotonics. PMID:20521799

Duque, Juan G; Parra-Vasquez, A Nicholas G; Behabtu, Natnael; Green, Micah J; Higginbotham, Amanda L; Price, B Katherine; Leonard, Ashley D; Schmidt, Howard K; Lounis, Brahim; Tour, James M; Doorn, Stephen K; Cognet, Laurent; Pasquali, Matteo

2010-06-22

85

Laser ablation process for single-walled carbon nanotube production.  

PubMed

Different types of lasers are now routinely used to prepare single-walled carbon nanotubes. The original method developed by researchers at Rice University used a "double-pulse laser oven" process. Several researchers have used variations of the lasers to include one-laser pulse (green or infrared), different pulse widths (ns to micros as well as continuous wave), and different laser wavelengths (e.g., CO2, or free electron lasers in the near to far infrared). Some of these variations are tried with different combinations and concentrations of metal catalysts, buffer gases (e.g., helium), oven temperatures, flow conditions, and even different porosities of the graphite targets. This article is an attempt to cover all these variations and their relative merits. Possible growth mechanisms under these different conditions will also be discussed. PMID:15296222

Arepalli, Sivaram

2004-04-01

86

Individual single-walled carbon nanotubes as electrochemical probes  

NASA Astrophysics Data System (ADS)

We have performed cyclic voltammetry measurements using individual single-walled carbon nanotubes as working electrodes. The nanotubes were first grown on silicon oxide substrates and contacted using titanium. An insulating layer was then deposited and sub-micron-sized windows opened, leaving only the sidewalls of selected nanotubes exposed. These devices were exposed to an electrolyte containing redox-active ferrocene derivatives and cyclic voltammetry measurements were performed. Our results suggest that metallic nanotubes behave as ideal cylindrical electrodes and exhibit a diffusion-limited redox current. The behavior of semiconducting nanotubes is more complex due to the interplay between band bending, quantum capacitance and the potential drop at the liquid-nanotube interface.

Lemay, S. G.; Heering, H. A.; Heller, I.; Kong, J.; Williams, K. A.; Dekker, C.

2004-03-01

87

Thermoelectric power of a single-walled carbon nanotubes rope.  

PubMed

In this work, a rope of single-walled carbon nanotubes is prepared by using a diamond wire drawing die. At atmospheric condition, the electrical conductance and the thermoelectric voltage of single-walled carbon nanotubes rope have been investigated with the hot-side temperature ranging from 292 to 380 K, and cold-side temperature at 292 K. For different temperatures in the range of 292 to 380 K at hot-side, the current-voltage curves are almost parallel to each other, indicating that the electrical conductance does not change. The dynamic characteristics of voltage at positive, zero and negative current bias demonstrate that a thermoelectric voltage is induced with a direction from hot- to cold-side. The induced thermoelectric voltage shows linear dependence on the temperature difference between hot- and cold-side. The thermoelectric power of single-walled carbon nanotubes rope is found to be positive and has a value about 17.8 +/- 1.0 microV/K. This result suggests the hole-like carriers in single-walled carbon nanotubes rope. This study will pave the way for single-walled carbon nanotubes based thermoelectric devices. PMID:23646631

Yu, Fang; Hu, Lijun; Zhou, Haiqing; Qiu, Caiyu; Yang, Huaichao; Chen, Minjiang; Lu, Jianglei; Sun, Lianfeng

2013-02-01

88

Electrochemical Sensing with Individual Single-Wall Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

The transport properties of molecular electronic devices can be strongly modulated by immersion in a liquid electrolyte. For example, early investigations with single-wall carbon nanotubes (SWNTs) used the electrolyte as a "liquid gate." That is, the conductance of SWNTs in a field-effect-transistor configuration was tuned via an electrochemical potential applied to the electrolyte. This concept was also extended to sensor applications in which molecules impinging upon the SWNT surface cause a rearrangement of screening ions and a corresponding change of the device conductance. In these approaches, the coupling between the device and the electrolyte is solely electrostatic, and no charge is transferred across the liquid-device interface. Here we demonstrate that individual SWNTs can also be used as electrodes for electron transfer reactions, that is, electrochemical reactions in which electrons are exchanged between a SWNT and redox-active molecules in solution. The rate of electron transfer to SWNTs is observed to be very fast. It can nonetheless be resolved in dc transport measurements due to the high diffusive flux of redox molecules resulting from the nanometer diameter of SWNTs. Interestingly, metallic and semiconducting SWNTs yield similar current-voltage characteristics; we show that this behaviour is consistent with theories of electron transfer in which the electronic structure of the SWNTs is explicitly taken into account. Finally, we demonstrate that noble metals can be controllably and selectively electrodeposited from aqueous solution unto individual single-wall carbon nanotubes, opening new routes for the functionalization of SWNT devices. Work done with K. Besteman, H. A. Heering, I. Heller, J. Kong, J.-O Lee, B. M. Quinn, F.G.M. Wiertz, K. A. Williams and C. Dekker.

Lemay, Serge

2005-03-01

89

Electrochemical charging of individual single-walled carbon nanotubes.  

PubMed

The influence of the electrode potential on the electronic structure of individual single-walled carbon nanotubes is studied using Raman spectroscopy. By analyzing the radial breathing mode intensity versus electrode potential profiles in the Raman spectra at many different laser excitation energies, we show that the charging of individual carbon nanotubes causes a broadening of the resonant Raman profiles (resonance window). This effect is observed for both a semiconducting and a metallic tube. The broadening of the resonance Raman profiles already begins at potentials where the first electronic states of a particular tube are filled or depleted. The important consequence of this effect is a striking difference between the Raman intensity versus potential profiles of metallic and semiconducting tubes. While for a metallic tube the intensity of the Raman signal is attenuated at potentials which deviate slightly from 0 V, for a semiconducting tube, the Raman intensity is significantly attenuated only after the electrode potential reaches the first van Hove singularity. Furthermore, for the metallic tube, a strong asymmetry is found in the bleaching of the Raman signal with respect to positive and negative potentials, which results from the different energy bandwidth for the pi* band and the pi band. PMID:19645423

Kalbac, Martin; Farhat, Hootan; Kavan, Ladislav; Kong, Jing; Sasaki, Ken-ichi; Saito, Riichiro; Dresselhaus, Mildred S

2009-08-25

90

Purification Procedures for Single-Wall Carbon Nanotubes.  

National Technical Information Service (NTIS)

This report summarizes the comparison of a variety of procedures used to purify carbon nanotubes. Carbon nanotube material is produced by the arc process and laser oven process. Most of the procedures are tested using laser-grown, single-wall nanotube (SW...

O. P. Gorelik P. Nikolaev S. Arepalli

2001-01-01

91

Fracture resistance of zigzag single walled carbon nanotubes  

Microsoft Academic Search

Carbon nanotubes (CNTs) are known to possess extraordinary strength, stiffness and ductility properties. Their fracture resistance is an important issue from the perspective of durability and reliability of CNT-based materials and devices. According to existing studies, brittle fracture is one of the important failure modes of single-walled carbon nanotube (SWNT) failure due to mechanical loading. However, based on the authors'

Qiang Lu; Baidurya Bhattacharya

2006-01-01

92

Photoconductivity of Single-Wall Carbon Nanotube Films  

Microsoft Academic Search

To date, there have been few reported measurements of the photoconductivity of carbon nantoube films due to the difficulty in obtaining a measurable signal using standard excitation sources. This is despite the fact that the absorption spectrum of carbon nanotubes films is widely available. Here, we describe measurements of the photoconductivity (PC) of single wall nanotube (SWNT) films using a

Aditya Mohite; Swapan Chakraborty; Gamini Sumanasekera; Bruce Alphenaar

2004-01-01

93

Band Gap Fluorescence from Individual Single-Walled Carbon Nanotubes  

Microsoft Academic Search

Fluorescence has been observed directly across the band gap of semiconducting carbon nanotubes. We obtained individual nanotubes, each encased in a cylindrical micelle, by ultrasonically agitating an aqueous dispersion of raw single-walled carbon nanotubes in sodium dodecyl sulfate and then centrifuging to remove tube bundles, ropes, and residual catalyst. Aggregation of nanotubes into bundles otherwise quenches the fluorescence through interactions

Michael J. O'Connell; Sergei M. Bachilo; Chad B. Huffman; Valerie C. Moore; Michael S. Strano; Erik H. Haroz; Kristy L. Rialon; Peter J. Boul; William H. Noon; Carter Kittrell; Jianpeng Ma; Robert H. Hauge; R. Bruce Weisman; Richard E. Smalley

2002-01-01

94

Purification of single-walled carbon nanotubes synthesized by the hydrogen arc-discharge method  

Microsoft Academic Search

A simple procedure for the purification of the single-walled carbon nanotube (SWNT) product synthesized by the hydrogen arc-discharge method was proposed and discussed. The procedure involves ultrasonication in alcohol, oxidation in fixed air, and soaking in hydrochloric acid. Most of the amorphous carbon and carbon nanoparticles as well as metal particles in the product was successfully removed, according to the

Pengxiang Hou; Chang Liu; Yu Tong; Shitao Xu; Min Liu; Huiming Cheng

2001-01-01

95

Finite element modeling of single-walled carbon nanotubes  

Microsoft Academic Search

A three-dimensional finite element (FE) model for armchair, zigzag and chiral single-walled carbon nanotubes (SWCNTs) is proposed. The model development is based on the assumption that carbon nanotubes, when subjected to loading, behave like space-frame structures. The bonds between carbon atoms are considered as connecting load-carrying members, while the carbon atoms as joints of the members. To create the FE

K. I. Tserpes; P. Papanikos

2005-01-01

96

Single-Wall Carbon Nanohorns and Nanocones  

Microsoft Academic Search

\\u000a In addition to sheet structures with purely hexagonal carbon rings, which\\u000a naturally form surfaces of zero Gaussian curvature such as sheets and tubes, a\\u000a graphenic membrane can also assume a conical shape whose apex is defined by one or\\u000a more disclinations taking the form of fivefold (or possibly smaller) rings.\\u000a Geometrically, just as a sheet of paper with a wedge

Masako Yudasaka; Sumio Iijima; Vincent H. Crespi

97

Thermal Conductivity of Single-Walled Carbon Nanotube \\/ Polyethylene Nanocomposites  

Microsoft Academic Search

The thermal conductivity of nanocomposites with single walled carbon nanotubes (SWNTs) and polyethylene are being investigated with attention to the effect of the degree of PE crystallinity and the alignment of both the PE and SWNT. The nanocomposites were prepared via the hot-coagulation method, resulting in a good dispersion of the SWNTs in the polymer matrix. Characterization methods include the

Reto Haggenmueller; Jesse J. Cugliotta

2005-01-01

98

Specific heat of single-walled carbon nanotubes  

Microsoft Academic Search

The specific heat of single-walled carbon nanotubes (SWNT's) is studied theoretically in this paper. Making use of the continuum model, phonon dispersion relations are derived numerically and analytically. Finally, expressions for specific heat versus temperature are derived theoretically, and we find that the lattice wave propagating along the length of the SWNT plays the principle role in deciding the value

Shengli Zhang; Minggang Xia; Shumin Zhao; Tao Xu; Erhu Zhang

2003-01-01

99

Gas Separation by Kinked Single-Walled Carbon Nanotubes  

Microsoft Academic Search

A kink model for gas separation is presented. Transport of pure nitrogen, oxygen and their mixture in single walled carbon nanotubes (SWCNTs) with a kink formed by bending is studied using molecular dynamics simulations. The results show that a kinked SWCNT results in transport resistance to nitrogen while allowing oxygen to pass even though the two gases have very similar

Z. Q. Zhang; H. W. Zhang

2010-01-01

100

Cutting of Single-Walled Carbon Nanotubes by Ozonolysis  

Microsoft Academic Search

Cutting of single-walled carbon nanotubes (SWNT) has been achieved by extensive ozonolysis at room temperature. Perfluoropolyether (PFPE) was selected as a medium for cutting SWNT due to its high solubility for ozone (O3). A mixture of 9 wt % of O3 in O2 was bubbled through a homogeneous suspension of pristine SWNT in PFPE, at room temperature. The intense disorder

Zheyi Chen; Kirk J. Ziegler; Jonah Shaver; Robert H. Hauge; Richard E. Smalley

2006-01-01

101

Localization and nonlinear transport in single walled carbon nanotube fibers  

Microsoft Academic Search

Electrical and magnetotransport properties of single walled carbon nanotube (SWCNT) fibers are reported. The dependencies of resistance on temperature can be approximated by the Mott law for three-dimensional variable range hopping (VRH) below 80 K and by typical law for fluctuation induced tunneling model within the range of 80-300 K. Both negative and positive magnetoresistances (MRs) were observed. At low

V. K. Ksenevich; V. B. Odzaev; Z. Martunas; D. Seliuta; G. Valusis; J. Galibert; A. A. Melnikov; A. D. Wieck; D. Novitski; M. E. Kozlov; V. A. Samuilov

2008-01-01

102

Macroscopic, Neat, Single-Walled Carbon Nanotube Fibers  

Microsoft Academic Search

Well-aligned macroscopic fibers composed solely of single-walled carbon nanotubes (SWNTs) were produced by conventional spinning. Fuming sulfuric acid charges SWNTs and promotes their ordering into an aligned phase of individual mobile SWNTs surrounded by acid anions. This ordered dispersion was extruded via solution spinning into continuous lengths of macroscopic neat SWNT fibers. Such fibers possess interesting structural composition and physical

Lars M. Ericson; Hua Fan; Haiqing Peng; Virginia A. Davis; Wei Zhou; Joseph Sulpizio; Yuhuang Wang; Richard Booker; Juraj Vavro; Csaba Guthy; A. Nicholas G. Parra-Vasquez; Myung Jong Kim; Sivarajan Ramesh; Rajesh K. Saini; Carter Kittrell; Gerry Lavin; Howard Schmidt; W. Wade Adams; W. E. Billups; Matteo Pasquali; Wen-Fang Hwang; Robert H. Hauge; John E. Fischer; Richard E. Smalley

2004-01-01

103

Revealing the Substructure of Single-Walled Carbon Nanotube Fibers  

Microsoft Academic Search

Single-walled carbon nanotubes (SWNTs) uniquely combine characteristics of polymers (e.g., they are molecules composed of repeat units) as well as nanoscale colloids (e.g., they are extremely stiff); because of these characteristics, they may qualify as the ideal building blocks for the long-sought Staudinger's \\

Yuhuang Wang; Lars M. Ericson; Carter Kittrell; Myung Jong Kim; Hongwei Shan; Hua Fan; Steve Ripley; Sivarajan Ramesh; Robert H. Hauge; W. Wade Adams; Matteo Pasquali; Richard E. Smalley

2005-01-01

104

Macroscopic neat single-wall carbon nanotube fibers  

Microsoft Academic Search

Measured and predicted properties of individual single wall carbon nanotubes (SWNT) suggest that bulk SWNT materials will exhibit a variety of exceptional properties. Due to the anisotropic nature of SWNTs, fibers are a logical candidate for these objects. The first ever macroscopic fibers, consisting entirely of SWNTs, were successfully produced and characterized. Nanotubes were dissolved at high concentrations (6--10 wt%)

Lars Martin Ericson

2004-01-01

105

Elastic properties of single-walled carbon nanotubes  

Microsoft Academic Search

Analytical expressions for the velocities of the longitudinal and the torsional sound waves in single-walled carbon nanotubes are derived using Born's perturbation technique within a lattice-dynamical model. These expressions are compared to the formulas for the velocities of the sound waves in an elastic hollow cylinder from the theory of elasticity to obtain analytical expressions for the Young's and shear

V. N. Popov; V. E. Van Doren; M. Balkanski

2000-01-01

106

Raman spectroscopy on isolated single wall carbon nanotubes  

Microsoft Academic Search

A review is presented on the resonance Raman spectra from one isolated single wall carbon nanotube. The reasons why it is possible to observe the spectrum from only one nanotube are given and the important structural information that is provided by single nanotube spectroscopy is discussed. Emphasis is given to the new physics revealed by the various phonon features found

M. S. Dresselhaus; G. Dresselhaus; A. Jorio; A. G. Souza Filho; R. Saito

2002-01-01

107

Protocol for the characterization of single-wall carbon nanotube material quality  

Microsoft Academic Search

Single wall carbon nanotubes (SWCNTs) can be synthesized and purified by a number of techniques, and always contain certain amount of impurities of varying composition (mostly metal catalyst and non-tubular carbon), as well as defects resulting from purification. Particular purification route also affects homogeneity of nanotube material and its dispersability in organic solvents, which are important in the subsequent application

Sivaram Arepalli; Pavel Nikolaev; Olga Gorelik; Victor G Hadjiev; Williams Holmes; Bradley Files; Leonard Yowell

2004-01-01

108

Large-scale production of single-walled carbon nanotubes by induction thermal plasma  

Microsoft Academic Search

High quality single-walled carbon nanotubes (SWNT) have been synthesized at large scales by the method of direct evaporation of carbon black and metallic catalyst mixtures, using induction thermal plasma technology. The processing system consists mainly of an RF plasma torch, which generates a plasma jet of extremely high temperature (~15 000 K), with a high energy density and abundance of

Keun Su Kim; German Cota-Sanchez; Christopher T. Kingston; Matej Imris; Benoit Simard; Gervais Soucy

2007-01-01

109

Resonant Electron Scattering by Defects in Single-Walled Carbon Nanotubes  

Microsoft Academic Search

We report the characterization of defects in individual metallic single-walled carbon nanotubes by transport measurements and scanned gate microscopy. A sizable fraction of metallic nanotubes grown by chemical vapor deposition exhibits strongly gate voltage-dependent resistance at room temperature. Scanned gate measurements reveal that this behavior originates from resonant electron scattering by defects in the nanotube as the Fermi level is

Marc Bockrath; Wenjie Liang; Dolores Bozovic; Jason H. Hafner; Charles M. Lieber; M. Tinkham; Hongkun Park

2001-01-01

110

Synthesis of Single-Wall Carbon Nanotubes from Diesel Soot  

NASA Astrophysics Data System (ADS)

We show that diesel soot can be recycled as a carbon source for the synthesis of single-wall carbon nanotubes (SWNTs). The synthesis of SWNTs was carried out by the laser vaporization of diesel soot. The presence of SWNTs was confirmed by Raman spectroscopy and transmission electron microscopy. SWNTs produced in this way should provide economic benefits and also contribute to a cleaner environment.

Uchida, Takashi; Ohashi, Ouji; Kawamoto, Hironori; Yoshimura, Hirofumi; Kobayashi, Ken-ichi; Tanimura, Makoto; Fujikawa, Naohiro; Nishimoto, Tetsuro; Awata, Kazuhiko; Tachibana, Masaru; Kojima, Kenichi

2006-10-01

111

Interlayer spacing anomaly of single-wall carbon nanohorn aggregate  

Microsoft Academic Search

Newly found single-wall carbon nanohorns (SWNH) are synthesized by a CO2 laser vaporization of a pure carbon target in an Ar gas. Purification method using centrifugal separation and structural features of aggregated form of SWNHs (SWNH aggregate) are studied in this Letter. Although the X-ray diffraction profile taken for highly purified SWNH aggregates does not show any sharp 002 diffraction

S. Bandow; F. Kokai; K. Takahashi; M. Yudasaka; L. C. Qin; S. Iijima

2000-01-01

112

Modification of single wall carbon nanotubes (SWNT) for hydrogen storage  

Microsoft Academic Search

Due to unique structural, mechanical and electrical properties of single wall carbon nanotubes, SWNTs, they have been proposed as promising hydrogen storage materials especially in automotive industries. This research deals with investing of CNT’s and some activated carbons hydrogen storage capacity. The CNT’s were prepared through natural gas decomposition at a temperature of 900?C over cobalt-molybdenum nanoparticles supported by nanoporous magnesium

A. M. Rashidi; A. Nouralishahi; A. A. Khodadadi; Y. Mortazavi; A. Karimi; K. Kashefi

2010-01-01

113

Single Wall Carbon Nano Tube Films and Coatings  

Microsoft Academic Search

Purified single wall carbon nano tubes (SWNTs) produced from the high-pressure carbon monoxide (HiPCO) process have been dissolved \\/dispersed in oleum. These solutions \\/dispersions were optically homogeneous and have been used to form stand-alone SWNT films. The washed, dried, and heat-treated films are isotropic. The scanning electron micrographs of the film surface shows that the nanotube ropes (or fibrils) of

T. V. Sreekumar; Satish Kumar; Lars M. Ericson; Richard E. Smalley

2002-01-01

114

Theoretical study on the combined systems of peanut-shaped carbon nanotubes encapsulated in single-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

The combined systems of peanut-shaped carbon nanotubes encapsulated in both semiconducting and metallic single-walled carbon nanotubes are investigated by using self-consistent field crystal orbital method based on the density functional theory. The investigation indicates that the interaction between the two constituents is mainly contributed by the ? orbitals. The encapsulation does not change the semiconducting or metallic nature of the single-walled carbon nanotubes, but significantly changes the band dispersion and decreases the frontier band width of the metallic one. The carrier mobility and mean free path of the metallic single-walled carbon nanotube increase greatly after the encapsulation. The calculated mobilities have the order of 103 cm2 V-1 s-1 for both of the semiconducting and metallic double-walled carbon nanotubes.

Wang, Guo; Huang, Yuanhe

2012-10-01

115

Assessing the pulmonary toxicity of single-walled carbon nanohorns  

SciTech Connect

Previous studies have suggested that single-walled carbon nanotubes (SWCNTs) may be pose a pulmonary hazard. We investigated the pulmonary toxicity of single-walled carbon nanohorns (SWCNHs), a relatively new carbon-based nanomaterial that is structurally similar to SWCNTs. Mice were exposed to 30 g of surfactant-suspended SWCNHs by pharyngeal aspiration and sacrificed 24 hours or 7 days post exposure. Total and differential cell counts and cytokine analysis of bronchoalveolar lavage fluid demonstrated a mild inflammatory response which was mitigated by day 7 post exposure. Whole lung microarray analysis demonstrated that SWCNH-exposure did not lead to robust changes in gene expression. Finally, histological analysis showed no evidence of granuloma formation or fibrosis following SWCNH aspiration. These combined results suggest that SWCNH is a relatively innocuous nanomaterial when delivered to mice in vivo using aspiration as a delivery mechanism.

Lynch, Rachel M [ORNL; Voy, Brynn H [ORNL; Glass-Mattie, Dana F [ORNL; Mahurin, Shannon Mark [ORNL; Saxton, Arnold [University of Tennessee, Knoxville (UTK); Donnel, Robert L. [University of Tennessee, Knoxville (UTK); Cheng, Mengdawn [ORNL

2007-01-01

116

Assessing the pulmonary toxicity of single-walled carbon nanohorns  

SciTech Connect

Previous studies have suggested that single-walled carbon nanotubes (SWCNTs) may pose a pulmonary hazard. We investigated the pulmonary toxicity of single-walled carbon nanohorns (SWCNHs), a relatively new carbon-based nanomaterial that is structurally similar to SWCNTs. Mice were exposed to 30 {micro}g of surfactant-suspended SWCNHs or an equal volume of vehicle control by pharyngeal aspiration and sacrificed 24 hours or 7 days post-exposure. Total and differential cell counts and cytokine analysis of bronchoalveolar lavage fluid demonstrated a mild inflammatory response which was mitigated by day 7 post-exposure. Whole lung microarray analysis demonstrated that SWCNH-exposure did not lead to robust changes in gene expression. Finally, histological analysis showed no evidence of granuloma formation or fibrosis following SWCNH aspiration. These combined results suggest that SWCNH is a relatively innocuous nanomaterial when delivered to mice in vivo using aspiration as a delivery mechanism.

Lynch, Rachel M [ORNL; Voy, Brynn H [ORNL; Glass-Mattie, Dana F [ORNL; Mahurin, Shannon Mark [ORNL; Saxton, Arnold [University of Tennessee, Knoxville (UTK); Donnel, Robert L. [University of Tennessee, Knoxville (UTK); Cheng, Mengdawn [ORNL

2007-01-01

117

Theory of electroabsorption in semiconducting single-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

Eletroabsorption (EA) is a standard nonlinear optical technique to probe the excitonic characteristics of semiconductors. In the context of single-walled carbon nanotubes (SWCNTs) the advantage of EA is that it can directly probe the excitons associated with higher bands, which lie in the continuum region of the lowest band, and cannot be probed by other nonlinear optical techniques like photoinduced absorption or two-photon absorption. Although currently it is still difficult to carry out EA experiments, because it requires separation of semiconducting SWCNTs from metallic ones, theoretical calculations can provide a benchmark results for future study. We have calculated EA for several S-SWCNTs with both zigzag and chiral tubes. For the lowest exciton we find the usual Stark shift, the emergence of absorption due to two-photon states and continuum band. We also find unusual and interesting behavior of the higher energy excitons from second band. L. Sebastian and G. Weiser, Phys. Rev. Lett. 46, 1156 (1981); D. Guo et al., Phys. Rev. B 48, 1433 (1993). J. W. Kennedy, Z. V. Vardeny, S. Collins, R. H. Baughman, H. Zhao, and S. Mazumdar, cond-mat/0505071.

Zhao, Hongbo; Mazumdar, Sumit

2006-03-01

118

Single-walled carbon nanotube as an effective quencher.  

PubMed

Over the past few years, single-walled carbon nanotubes (SWNTs) have been the focus of intense research motivated by their unique physical and chemical properties. This review specifically summarizes recent progress in the development of fluorescence biosensors that integrate the quenching property of SWNTs and the recognition property of functional nucleic acids. SWNTs are substantially different from organic quenchers, showing superior quenching efficiency for a variety of fluorophores, with low background and high signal-to-noise ratio, as well as other advantages derived from the nanomaterial itself. As the second key component of biosensors, functional nucleic acids can bind to either their complementary DNA or a target molecule with the ability to recognize a broad range of targets from metal ions to organic molecules, proteins, and even live cells. By taking advantage of the strengths and properties of both SWNTs and nucleic acid based aptamers, a series of fluorescence biosensors have been designed and fabricated for the detection of a broad range of analytes with high selectivity and sensitivity. PMID:19898820

Zhu, Zhi; Yang, Ronghua; You, Mingxu; Zhang, Xiaoling; Wu, Yanrong; Tan, Weihong

2009-11-08

119

Electron transport in single-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

We present electron transport experiments on single walled carbon nanotubes (SWNTs). By measuring the linear scaling of resistance with length, we determine an unusually long mean free path of Lm ˜1 mum at room temperature. From the temperature dependence of the mean free path for over 10 samples we show that inelastic scattering with acoustic phonons are the main source of scattering at room temperature and experimentally determine the electron-acoustic phonon strength. Disorder ultimately limits the low temperature mean free path (Lm ˜10 mum), which we show by employing scanning gate microscopy. We analyze the non-linear scaling of resistance with length and temperature to further elucidate the nature of this disorder. In general, we find that transport in 1-dimension is dominated by the strongest defect along the channel. For larger source-drain voltage (VSD > 0.2 V), we show that L m is significantly reduced in both metallic and semiconducting SWNTs, due to electrons scattering with the higher energy phonons. In semiconducting samples, when the Fermi energy is close to the energy band gap, we observe an anomalous conductance dip. Finally, we utilize locally controlled gate structures to fabricate a series of tunable barriers to form a superlattice and observe its mini-band structure superimposed on that of the nanotubes.

Purewal, Meninder S.

120

Optoelectronic properties of single-wall carbon nanotubes.  

PubMed

Single-wall carbon nanotubes (SWCNTs), with their uniquely simple crystal structures and chirality-dependent electronic and vibrational states, provide an ideal laboratory for the exploration of novel 1D physics, as well as quantum engineered architectures for applications in optoelectronics. This article provides an overview of recent progress in optical studies of SWCNTs. In particular, recent progress in post-growth separation methods allows different species of SWCNTs to be sorted out in bulk quantities according to their diameters, chiralities, and electronic types, enabling studies of (n,m)-dependent properties using standard macroscopic characterization measurements. Here, a review is presented of recent optical studies of samples enriched in 'armchair' (n = m) species, which are truly metallic nanotubes but show excitonic interband absorption. Furthermore, it is shown that intense ultrashort optical pulses can induce ultrafast bandgap oscillations in SWCNTs, via the generation of coherent phonons, which in turn modulate the transmission of a delayed probe pulse. Combined with pulse-shaping techniques, coherent phonon spectroscopy provides a powerful method for studying exciton-phonon coupling in SWCNTs in a chirality-selective manner. Finally, some of the basic properties of highly aligned SWCNT films are highlighted, which are particularly well-suited for optoelectronic applications including terahertz polarizers with nearly perfect extinction ratios and broadband photodetectors. PMID:22911973

Nanot, Sébastien; Hároz, Erik H; Kim, Ji-Hee; Hauge, Robert H; Kono, Junichiro

2012-08-22

121

Palladium Nanoparticles Decorated Single-Walled Carbon Nanotube Hydrogen Sensor  

Microsoft Academic Search

We developed a simple and cost-effective fabrication technique to construct a hydrogen nanosensor by decorating single-walled carbon nanotubes with Pd nanoparticles. By varying the sensor's synthesis conditions (e.g., Pd electrodeposition charge, deposition potential, and initial baseline resistance of the SWNT network), the sensing performance was optimized. The optimized sensor showed excellent sensing properties toward hydrogen (¢R\\/R of 0.42%\\/ppm) with a

Syed Mubeen; Ting Zhang; Bongyoung Yoo; Marc A. Deshusses; Nosang V. Myung

2007-01-01

122

Electron-induced cutting of single-walled carbon nanotubes  

Microsoft Academic Search

Electron beam irradiation with moderate fluences of approximately 1016–1017 electrons per cm2 is used for controllable, bulk-scale cutting of single-walled carbon nanotubes (SWCNTs). The effectiveness of high energy electron irradiation in cutting SWCNTs is dependent on the nature of the sidewall. While pristine nanotubes are very stable under irradiation conditions, ozonated SWCNTs combined with a moderate fluence of electrons resulted

Urs Rauwald; Jonah Shaver; Donald A. Klosterman; Zheyi Chen; Carlos Silvera-Batista; Howard K. Schmidt; Robert H. Hauge; Richard E. Smalley; Kirk J. Ziegler

2009-01-01

123

Quantized Phonon Spectrum of Single-Wall Carbon Nanotubes  

Microsoft Academic Search

The electronic spectra of carbon nanotubes and other nanoscale systems are quantized because of their small radii. Similar quantization in the phonon spectra has been difficult to observe because of the far smaller energy scale. We probed this regime by measuring the temperature-dependent specific heat of purified single-wall nanotubes. The data show direct evidence of one-dimensional quantized phonon subbands. Above

J. Hone; B. Batlogg; Z. Benes; A. T. Johnson; J. E. Fischer

2000-01-01

124

Specific heat of single-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

The specific heat of single-walled carbon nanotubes (SWNT’s) is studied theoretically in this paper. Making use of the continuum model, phonon dispersion relations are derived numerically and analytically. Finally, expressions for specific heat versus temperature are derived theoretically, and we find that the lattice wave propagating along the length of the SWNT plays the principle role in deciding the value of the specific heat. Our theoretical results agree well with experimental data [Science 289,1730 (2000)].

Zhang, Shengli; Xia, Minggang; Zhao, Shumin; Xu, Tao; Zhang, Erhu

2003-08-01

125

Phonon and thermal properties of achiral single wall carbon nanotubes  

Microsoft Academic Search

A detailed theoretical study of the phonon and thermal properties of achiral single wall carbon nanotubes has been carried\\u000a out using force constant model considering up to third nearest-neighbor interactions. We have calculated the phonon dispersions,\\u000a density of states, radial breathing modes (RBM) and the specific heats for various zigzag and armchair nanotubes, with radii\\u000a ranging from 2.8 Å to

Prapti Saxena; Sankar P Sanyal

2006-01-01

126

Thermal properties of single-walled carbon nanotube crystal  

Microsoft Academic Search

In this work, the thermal properties of a single-walled carbon nanotube (SWCNT) crystal are studied. The thermal conductivity of the SWCNT crystal is found to have a linear dependence on temperature in the temperature range from 1.9 K to 100.0 K. In addition, a peak (658 W\\/mK) is found at a temperature of about 100.0 K. The thermal conductivity decreases

Li-Jun Hu; Ji Liu; Zheng Liu; Cai-Yu Qiu; Hai-Qing Zhou; Lian-Feng Sun

2011-01-01

127

Phonons in ropes of single-wall carbon nanotubes  

Microsoft Academic Search

The vibrational density of states (DOS) of ropes of single-wall carbon nanotubes (SWNT) was obtained from inelastic neutron scattering data. The spectrum covers the entire predicted range of possible phonon energies from 0 to 225 meV. The DOS is similar to that of graphite above 40 meV, and markedly different below, where inter-tube features are clearly observed at 22 and

Zdenek Benes

2001-01-01

128

Single-wall carbon nanotube coating on a pyroelectric detector  

Microsoft Academic Search

Carbon single-wall nanotubes (SWNTs) are studied as the thermal-absorption coating on a large area pyroelectric detector. The SWNTs were produced by a laser vaporization method and dispersed onto the detector surface by use of a simple airbrush technique. The detector was based on a 1-cm-diameter, 60-m-thick lithium tantalate disk having nickel electrodes. We report the spectral responsivity of the detector

Chaiwat Engtrakul; Thomas Gennett

2005-01-01

129

Impedance of Single-Walled Carbon Nanotube Fibers  

Microsoft Academic Search

Impedance measurements of single-wall carbon nanotube (SWCNT) fibers were carried out in the frequency range of 20?10 Hz at temperatures 4.2 < T < 300 K and in the range of applied bias voltage 0?5 V. It was found that in the low frequency range (f ˜ 1–20 kHz) at low temperatures and at bias voltage U > 2 V

V. K. Ksenevich; N. I. Gorbachuk; N. A. Poklonski; V. A. Samuilov; M. E. Kozlov; A. D. Wieck

2012-01-01

130

Single-walled carbon nanotube fibers, films and balls  

Microsoft Academic Search

Well-defined fibers and films of single-walled carbon nanotubes (SWNTs) with high purity and narrow diameter distributions were obtained from the strand-like raw soot produced by a dc arc-discharge method. These architectures made up of SWNTs have very uniform smooth surfaces. When the strand-like product was placed on a silicon substrate, dipped into water, treated ultrasonically, and then dried in air,

Lunhui Guan; Huanjun Li; Zujin Shi; Zhennan Gu

2007-01-01

131

"Zero-dimensional" single-walled carbon nanotubes.  

PubMed

The shorter, the more dispersible: An iterative, emulsion-based shortening technique has been used to reduce the length of single-walled carbon nanotubes (SWNTs) to the same order of magnitude as their diameter (ca. 1?nm), thus achieving an effectively "zero-dimensional" structure with improved dispersibility and, after hydroxylation, long-term water solubility. Finally, zero-dimensional SWNTs were positively identified using mass spectrometry for the first time. PMID:24038731

Kamalasanan, Kaladhar; Gottardi, Riccardo; Tan, Susheng; Chen, Yanan; Godugu, Bhaskar; Rothstein, Sam; Balazs, Anna C; Star, Alexander; Little, Steven R

2013-09-05

132

Photoemission electron microscopy of individual single-walled carbon nanotubes  

Microsoft Academic Search

Individual suspended single-walled carbon nanotubes were observed by means of C 1s and secondary electron photoemission electron microscopy. No band bending was observed in the images, suggesting that the depletion width near the catalytic Fe\\/nanotube or substrate Si\\/nanotube contact is comparable to the spatial resolution of 40nm or less. Work function differences between the nanotubes were clearly observed in secondary

Satoru Suzuki; Yoshio Watanabe; Yoshikazu Homma; Shin-ya Fukuba; Andrea Locatelli; Stefan Heun

2005-01-01

133

Single-walled carbon nanotubes exhibit strong antimicrobial activity.  

PubMed

We provide the first direct evidence that highly purified single-walled carbon nanotubes (SWNTs) exhibit strong antimicrobial activity. By using a pristine SWNT with a narrow diameter distribution, we demonstrate that cell membrane damage resulting from direct contact with SWNT aggregates is the likely mechanism leading to bacterial cell death. This finding may be useful in the application of SWNTs as building blocks for antimicrobial materials. PMID:17658863

Kang, Seoktae; Pinault, Mathieu; Pfefferle, Lisa D; Elimelech, Menachem

2007-07-21

134

The production of horizontally aligned single-walled carbon nanotubes  

Microsoft Academic Search

The current progress on the production of aligned single-walled carbon nanotubes (SWCNTs), particularly the horizontally aligned ones, is reviewed. There are two main categories for the alignment of SWCNTs: the post synthesis assembly and the in situ growth approaches. The post synthesis assembly approach mainly involves dispersing SWCNTs in solutions and aligning SWCNTs using spin-coating, Langmuir–Blodgett assembly, mechanical shearing, or

Yanfeng Ma; Bin Wang; Yingpeng Wu; Yi Huang; Yongsheng Chen

2011-01-01

135

Static polarizabilities of single-wall carbon nanotubes  

Microsoft Academic Search

The static electric polarizability tensor of single-wall carbon nanotubes is calculated within the random-phase approximation using a simple tight-binding model and a classical correction to include local fields. We find that the polarizability for constant fields parallel to the cylindrical axis is highly dependent on the details of the tube`s electronic structure. In contrast, the polarizability for fields perpendicular to

Lorin Benedict; Steven Louie; Marvin Cohen

1995-01-01

136

Band theory of single-walled carbon nanotubes  

Microsoft Academic Search

In this paper, a curvilinear coordinate system is used in space and in k-space to study the energy band of single-walled carbon nanotubes wrapped at a helical angle. Using this method, a general function of the bandgap associated with the radius of the tube and the helical angle is derived based on the tight-binding theory. The three-dimensional hexagonal Brillouin zone

Ming Zang

2005-01-01

137

Raman Spectroscopy of Single Wall Carbon Nanotubes Upon Electrochemical Doping  

Microsoft Academic Search

Single wall carbon nanotubes in vacuum filtered papers were studied using Raman scattering. Spectra of the tangential displacement modes (TDM: ˜1580cm-1) and radial breathing modes (RBM: ˜200cm-1) were measured at several excitation wavelengths between 476.5nm and 676.4nm, and the mean diameter and diameter distribution of the tubes were determined from theoretical predictions of the RBM frequencies. The effects of electrochemical

W. Joshua Kennedy; Valy Vardeny; Alan Dalton; Ray Baughman; Edgar Munoz; Anvar Zakhidov

2002-01-01

138

Reversible separation of single-walled carbon nanotubes in bundles  

NASA Astrophysics Data System (ADS)

We show that electrostatic charging of nanotubes and the consequent repulsion can lead to reversible separation of individual single-walled carbon nanotubes in bundles. Low-energy electron beam irradiation leads to this completely reversible phenomenon. A simple semianalytical model is used to explain the observed separation mechanism. The reversibility of the separation process is attributed to discharging and thermal-fluctuation induced motion of the nanotubes in ambient air. Further, the separation impacts the electrical conductance of small nanotube bundled devices.

Sahoo, Sangeeta; Maranganti, Ravi; Lastella, Sarah; Mallick, Govind; Karna, Shashi; Sharma, Pradeep; Ajayan, Pulickel M.

2008-08-01

139

Importance of oxygen in the metal-free catalytic growth of single-walled carbon nanotubes from SiO(x) by a vapor-solid-solid mechanism.  

PubMed

To understand in-depth the nature of the catalyst and the growth mechanism of single-walled carbon nanotubes (SWCNTs) on a newly developed silica catalyst, we performed this combined experimental and theoretical study. In situ transmission electron microscopy (TEM) observations revealed that the active catalyst for the SWCNT growth is solid and amorphous SiO(x) nanoparticles (NPs), suggesting a vapor-solid-solid growth mechanism. From in situ TEM and chemical vapor deposition growth experiments, we found that oxygen plays a crucial role in SWCNT growth in addition to the well-known catalyst size effect. Density functional theory calculations showed that oxygen atoms can enhance the capture of -CH(x) and consequently facilitate the growth of SWCNTs on oxygen-containing SiO(x) NPs. PMID:21155566

Liu, Bilu; Tang, Dai-Ming; Sun, Chenghua; Liu, Chang; Ren, Wencai; Li, Feng; Yu, Wan-Jing; Yin, Li-Chang; Zhang, Lili; Jiang, Chuanbin; Cheng, Hui-Ming

2010-12-14

140

Tunable Resonant Raman Scattering From Singly Resonant Single Wall Carbon Nanotubes  

Microsoft Academic Search

We perform tunable resonant Raman scattering on 17 semiconducting and seven metallic singly resonant single wall carbon nanotubes. The measured scattering cross section as a function of laser energy provides information about a tube's electronic structure, the lifetime of intermediate states involved in the scattering process, and also the energies of zone center optical phonons. Recording the scattered Raman signal

Yan Yin; Andy G. Walsh; A. Nick Vamivakas; Stephen B. Cronin; Michael Tinkham; Wolfgang Bacsa; M. S. nl; Bennett B. Goldberg; Anna K. Swan

2006-01-01

141

COMPUTER SIMULATION OF THE SPECIFIC HEAT OF SINGLE WALLED CARBON NANOTUBES  

Microsoft Academic Search

Computer simulation of the specific heat at constant volume (Cv) as a function of temperature is carried out and analysed in detail for the different types (semiconductor and metallic) of single-walled carbon nanotubes (SWCNT). In particular, at the low temperatures (up to 10 K) we have obtained the linear Cv(T) dependence for all types of the SWCNT. With temperature increase

Yu. I. Prylutskyy; O. V. Ogloblya; M. V. Makarets

142

Selectivity of chemical oxidation attack of single-wall carbon nanotubes in solution  

Microsoft Academic Search

Chemical oxidation of single wall carbon nanotubes (SWNTs), produced with the HiPco method, is studied by resonance Raman scattering. The analysis of the radial breathing mode makes it possible to assign the observed bands to metallic and semiconducting SWNTs and to suggest the chiral indices of SWNTs contributing to the spectra. On this basis we observe that the most important

Enzo Menna; Federico della Negra; Michela dalla Fontana; Moreno Meneghetti

2003-01-01

143

Growth of Single-Walled Carbon Nanotubes from Discrete Catalytic Nanoparticles of Various Sizes  

Microsoft Academic Search

Discrete catalytic nanoparticles with diameters in the range of 1 -2 nm and 3-5 nm respectively are obtained by placing controllable numbers of metal atoms into the cores of apoferritin, and used for growth of single- walled carbon nanotube (SWNTs) on substrates by chemical vapor deposition (CVD). Atomic force microscopy (AFM), transmission electron microscopy (TEM), and micro-Raman spectroscopy are used

Yiming Li; Woong Kim; Yuegang Zhang; Marco Rolandi; Dunwei Wang; Hongjie Dai

2001-01-01

144

Room temperature methane detection using palladium loaded single-walled carbon nanotube sensors  

Microsoft Academic Search

Single-walled carbon nanotubes (SWNTs) loaded with palladium (Pd) nanoparticles are used for detection of methane ranging from 6 to 100 ppm in air at room temperature. The Pd-SWNT nanosensors show advantages over conventional catalytic beads and metal oxide sensors for methane detection in terms of reduced size and power consumption by a factor of 100 and sensitivity by a factor

Yijiang Lu; Jing Li; Jie Han; H.-T. Ng; Christie Binder; Christina Partridge; M. Meyyappan

2004-01-01

145

Covalently Bridging Gaps in Single-Walled Carbon Nanotubes with Conducting Molecules  

Microsoft Academic Search

Molecular electronics is often limited by the poorly defined nature of the contact between the molecules and the metal surface. We describe a method to wire molecules into gaps in single-walled carbon nanotubes (SWNTs). Precise oxidative cutting of a SWNT produces carboxylic acid-terminated electrodes separated by gaps of <=10 nanometers. These point contacts react with molecules derivatized with amines to

Xuefeng Guo; Joshua P. Small; Jennifer E. Klare; Yiliang Wang; Meninder S. Purewal; Iris W. Tam; Byung Hee Hong; Robert Caldwell; Limin Huang; Stephen O'Brien; Jiaming Yan; Ronald Breslow; Shalom J. Wind; James Hone; Philip Kim; Colin Nuckolls

2006-01-01

146

Science of single-wall carbon nanotubes: Purification, characterization and chemistry  

Microsoft Academic Search

Characterization of raw nanotube materials produced by different methods is demonstrated. Depending on the production methods, tubes of different diameters can be produced. Purification of single wall carbon nanotubes produced by laser-oven and HiPco process is also discussed. Metal catalyzed oxidation at low temperature has been shown to selectively remove non-SWNT carbon and permit extraction of metals with concentrated HCl.

Ivana Wan-Ting Chiang

2001-01-01

147

Measuring particle size-dependent physicochemical structure in airborne single walled carbon nanotube agglomerates  

Microsoft Academic Search

As-produced single-walled carbon nanotube (SWCNT) material is a complex matrix of carbon nanotubes, bundles of nanotubes (nanoropes),\\u000a non-tubular carbon and metal catalyst nanoparticles. The pulmonary toxicity of material released during manufacture and handling\\u000a will depend on the partitioning and arrangement of these components within airborne particles. To probe the physicochemical\\u000a structure of airborne SWCNT aggregates, a new technique was developed

Andrew D. Maynard; Bon Ki Ku; Mark Emery; Mark Stolzenburg; Peter H. McMurry

2007-01-01

148

Measuring particle size-dependent physicochemical structure in airborne single walled carbon nanotube agglomerates  

Microsoft Academic Search

As-produced single-walled carbon nanotube (SWCNT) material is a complex matrix of carbon nanotubes, bundles of nanotubes (nanoropes),\\u000a non-tubular carbon and metal catalyst nanoparticles. The pulmonary toxicity of material released during manufacture and handling\\u000a will depend on the partitioning and arrangement of these components within airborne particles. To probe the physicochemical\\u000a structure of airborne SWCNT aggregates, a new technique was developed

Andrew D. Maynard; Bon Ki Ku; Mark Emery; Mark Stolzenburg; Peter H. McMurry

149

Nose–Hoover thermostat length effect on thermal conductivity of single wall carbon nanotubes  

Microsoft Academic Search

Non-equilibrium molecular dynamics simulations are used to determine the thermal conductivities of single wall carbon nanotubes. By fixing opposing ends of an armchair single wall carbon nanotube with a Nose–Hoover thermostat, the length dependence of thermal conductivities of single wall carbon nanotubes were studied in a vacuum. Specifically, single wall carbon nanotubes of 12.3nm, 24.6nm, and 36.9nm lengths with varying

Robert A. Shelly; Kasim Toprak; Yildiz Bayazitoglu

2010-01-01

150

40 CFR 721.10156 - Single-walled carbon nanotubes (generic).  

Code of Federal Regulations, 2010 CFR

...2009-07-01 false Single-walled carbon nanotubes (generic). 721.10156 Section...721.10156 Single-walled carbon nanotubes (generic). (a) Chemical substance...generically as single-walled carbon nanotubes (PMN P-08-328) is subject...

2009-07-01

151

Near-edge X-ray absorption fine structure spectroscopy-assisted purification of single-walled carbon nanotubes  

Microsoft Academic Search

Single-walled carbon nanotubes were produced by the conventional arc discharge method, and purified with a two-step treatment. First, the raw soot containing single-walled carbon nanotubes was burned up at ca. 350 °C in air to remove amorphous carbon, and then it was treated by strong acidic solvents to remove metal catalysts. Near-edge X-ray absorption fine structure spectroscopy was applied to analyze

Dong-Wei Yan; Jun Zhong; Chun-Ru Wang; Zi-Yu Wu

2007-01-01

152

Aligned arrays of single walled carbon nanotubes for transparent electronics  

NASA Astrophysics Data System (ADS)

Single walled carbon nanotubes have garnered substantial interest in the electronic materials research community due to their unparalleled intrinsic electrical properties. In addition, their mechanical robustness and thin geometries make SWNTs ideal candidates for transparent electronics. Aligned arrays of SWNTs grown via chemical vapor deposition (CVD) on quartz enable device uniformity and wafer scale integration with existing commercial semiconductor processing methods. A crucial roadblock in incorporation of SWNTs in commercial electronics has been the co-existence of metallic and semiconducting SWNTs. Demanding device metrics in high performance and complex integrated electrical devices, sensors, and other applications dictate the necessity of pristine, purely semiconducting arrays of SWNTs. By exploiting a novel process in nanoscale flow of thin film organic coatings, we have demonstrated a method to purify as-grown aligned arrays to produce such as result. Comparison with single nanotube statistics, characterization using a novel thermal scanning probe microscopy technique, as well as corroboration with thermal modeling validated the result. Thin film field effect transistors exhibiting mobilities exceeding ~1000cm2/Vs and on/off ratios exceeding 10,000 were fabricated using the purified semiconducting SWNTs. This manuscript reviews some of these results, which represent the first successful demonstration of purification of aligned arrays of SWNTs, in a robust and scalable scheme that allows integration of aligned arrays into complex, high performance electrical devices. We separately also describe new results on the advanced development of soft lithography techniques with the ability to transfer print aligned arrays of SWNTs onto transparent substrates after synthesis and processing, thereby completing a direct pathway to achieve complex, high performance, and highly integrated transparent SWNTs electronics, sensors, or other devices.

Du, Frank; Rogers, John A.

2013-06-01

153

Self-assembling Functionalized Single-walled Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

Single-walled carbon nanotubes (SWCNTs) are promising bottom-up building materials due to their superior properties. However, the lack of an effective method to arrange large quantities of SWCNTs poses an obstacle toward their applications. Existing studies to functionalize, disperse, position, and assemble SWCNTs provide a broad understandings regarding SWCNTs behavior, especially in aqueous electrolyte solution. Inspired by ionic polymer metal composite (IPMC) materials, this dissertation envisions fabrication of orderly SWCNTs network structure via their ionic clustering-mediated self-assembly. SWCNTs tend to bundle together due to inter-nanotube VDW attractions, which increase with nanotube length. The author seeks short SWCNTs with long chain molecules bearing ionic termini to facilitate debundling and self-assembly in aqueous electrolyte solution through end-clustering. First, a simple model was applied based on essential physical factors. The results indicated that SWCNTs must be shorter than ˜100 nm to achieve stable network structures. Experiments were then carried out based upon the results. Short SWCNTs (50-100 nm) were end-functionalized with hexaethylene glycol (HEG) linkers bearing terminal carboxylate anions. Both 2D and 3D network structures were observed after placing the functionalized SWCNTs in aqueous electrolyte (sodium ion). The network structures were characterized by microscopic and spectroscopic methods. A novel approach was applied via electron tomography to study the 3D structures of SWCNTs structure in aqueous electrolyte. Free energy analysis of the SWCNTs network structure was implemented with the assistance of both analytical tools and molecular simulations. The results indicate that, when a cluster is formed by three functionalized SWCNTs ends, the resulting network structure is most stable. Indeed, 72% of the clusters/joints were formed by three nanotubes, as observed in experiments. Finally, Monte Carlo simulations of coarse-grained SWCNTs were implemented to understand the behavior of SWCNTs. SWCNTs clusters were observed as a result of this simulation.

Gao, Yan

154

Formation of single-wall carbon nanotube superbundles  

SciTech Connect

Since their discovery in 1993, carbon single-wall nanotubes (SWNTs) have been of great interest because of their expected novel electronic, mechanical, and gas adsorption properties. Difficulties arise in measuring these various properties because the SWNTs currently available for analyses have very small bundle sizes (10--20 nm) and are typically in random orientations. A vital step for the industrial application of SWNTs is to align the individual tubes into bundles of a size that allows facile measurement of the various physical and chemical properties. This paper is the first to illustrate a set of procedures for the preparation and isolation of aligned SWNT superbundles.

Gennett, T.; Dillon, A.C.; Alleman, J.L.; Jones, K.M.; Hasoon, F.S.; Heben, M.J.

2000-03-01

155

Thermal Degradation of Single-Walled Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

An optical absorbance technique was used to study the burning temperature and burning mechanism of vertically aligned single-walled carbon nanotube (VA-SWNT) films. The use of this simple optical method is shown to be consistent with the standard thermogravimetric analysis (TGA) method, but it can be applied to a very small amount of SWNTs. Experimental results indicate that burning of the VA-SWNTs is not localized, but occurs throughout the film. Furthermore, thick films have a slightly higher burning temperature than thin films synthesized under the same conditions. This is believed to be due to a higher bundle density and more uniform distribution of SWNTs within thicker films.

Duong, Hai M.; Einarsson, Erik; Okawa, Jun; Xiang, Rong; Maruyama, Shigeo

2008-04-01

156

Electronic structure of intercalated single-wall carbon nanotubes  

NASA Astrophysics Data System (ADS)

We present recent studies of the electronic structure and optical properties of intercalated single-wall carbon nanotubes using high resolution electron energy-loss spectroscopy (EELS) in transmission and optical absorption spectroscopy. Results on nanotubes intercalated with potassium and iron (III) chloride are presented. Changes in the nanotube electronic structure were monitored in-situ by optical absorption and EELS. The modulation of the filling of van Hove singularities is reflected by the intensity variations of the optical excitations. The intensity of the interband transitions is dramatically affected, demonstrating the possibility of tuning the Fermi level to specific bands upon doping.

Liu, X.; Pichler, T.; Knupfer, M.; Golden, M. S.; Fink, J.; Kataura, H.

2002-10-01

157

RF response of single-walled carbon nanotubes.  

PubMed

We present for the first time an in-depth study of the RF response of a single-walled carbon nanotube (SWCNT) rope. Our novel electrode design, based on a tapered coplanar approach, allows for single tube measurements well into the GHz regime, minimizing substrate-related parasitics. From the analysis of the S-parameters, the ac transport mechanism in the range 30 kHz to 6 GHz is established. This work is an essential prerequisite for the fabrication of high-speed devices based on bundles of nanowires or low-dimensional structures. PMID:17705549

Gomez-Rojas, Luis; Bhattacharyya, Somnath; Mendoza, Ernest; Cox, David C; Rosolen, J Mauricio; Silva, S Ravi P

2007-08-18

158

Breaking single-walled carbon nanotube bundles by Joule heating  

NASA Astrophysics Data System (ADS)

Electrical breakdown induced by Joule heating was employed to make a well-aligned surface structure from single-walled carbon nanotube (SWCNT) bundles. The surfaces at the breaking ends are tip abundant and composed of SWCNTs of high quality. In addition, the radial breathing mode frequencies of the CNT tips have a downshift than the as-grown SWCNTs, due to the higher thermal stability of wider SWCNTs and the strong intertube interactions. The ends can provide emission currents of about 100 ?A, and a pixel based on these potential electron emitters was developed for lateral field emission displays.

Wei, Yang; Liu, Peng; Jiang, Kaili; Liu, Liang; Fan, Shoushan

2008-07-01

159

Superconductivity in 4 angstrom single-walled carbon nanotubes.  

PubMed

Investigation of the magnetic and transport properties of single-walled small-diameter carbon nanotubes embedded in a zeolite matrix revealed that at temperatures below 20 kelvin, 4 angstrom tubes exhibit superconducting behavior manifest as an anisotropic Meissner effect, with a superconducting gap and fluctuation supercurrent. The measured superconducting characteristics display smooth temperature variations owing to one-dimensional fluctuations, with a mean-field superconducting transition temperature of 15 kelvin. Statistical mechanic calculations based on the Ginzburg-Landau free-energy functional yield predictions that are in excellent agreement with the experiments. PMID:11431560

Tang, Z K; Zhang, L; Wang, N; Zhang, X X; Wen, G H; Li, G D; Wang, J N; Chan, C T; Sheng, P

2001-06-29

160

Microwave Conductivity of Single Wall Carbon Nanotube Arrays  

NASA Astrophysics Data System (ADS)

We have measured the microwave conductivity spectra of carbon nanotube (CNT) parallel arrays from room temperature to 4K. Single wall CNTs were assembled by AC dielectrophoresis into parallel arrays of individual CNTs and ropes spanning the electrodes of coplanar waveguides (CPWs). The CPW complex reflection and transmission coefficients were measured from 0.1 to 50 GHz. Measurements of identical bare CPWs were utilized to calculate the frequency dependent complex conductivity and power dissipation of the CNT arrays and provide estimates of these quantities for individual CNTs in this configuration. Small loss due to the CNT arrays is consistently measured and increases with frequency.

Highstrete, C.; Shaner, E. A.; Lee, Mark; Jones, F. E.; Dentinger, P. M.; Talin, A. A.

2007-03-01

161

Structural anisotropy of magnetically aligned single wall carbon nanotube films  

NASA Astrophysics Data System (ADS)

Thick films of aligned single wall carbon nanotubes and ropes have been produced by filtration/deposition from suspension in strong magnetic fields. We measured mosaic distributions of rope orientations in the film plane, for samples of different thicknesses. For an ~1 ?m film the full width at half maximum (FWHM) derived from electron diffraction is 25°-28°. The FWHM of a thicker film (~7 ?m) measured by x-ray diffraction is slightly broader, 35+/-3°. Aligned films are denser than ordinary filter-deposited ones, and much denser than as-grown material. Optimization of the process is expected to yield smaller FWHMs and higher densities.

Smith, B. W.; Benes, Z.; Luzzi, D. E.; Fischer, J. E.; Walters, D. A.; Casavant, M. J.; Schmidt, J.; Smalley, R. E.

2000-07-01

162

Electronic Structures of Single-Walled Carbon Nanotubes Determined by NMR  

Microsoft Academic Search

Single-walled carbon nanotubes were studied by 13C nuclear magnetic resonance (NMR). Two types of 13C nuclear spins were identified with different spin-lattice relaxation rates. The fast-relaxing component, assigned to metallic tubes, followed the relaxation behavior expected in metals, and the density-of-states at the Fermi level increased with decreasing tube diameter. The slow-relaxing component has a significantly lower density-of-states at the

X.-P. Tang; A. Kleinhammes; H. Shimoda; L. Fleming; K. Y. Bennoune; S. Sinha; C. Bower; O. Zhou; Y. Wu

2000-01-01

163

Resonant coherent phonon spectroscopy of single-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

Using femtosecond pump-probe spectroscopy with pulse-shaping techniques, one can generate and detect coherent phonons in chirality-specific semiconducting single-walled carbon nanotubes. The signals are resonantly enhanced when the pump photon energy coincides with an interband exciton resonance, and the analysis of such data provides a wealth of information on the chirality dependence of light absorption, phonon generation, and phonon-induced band-structure modulations. To explain our experimental results, we have developed a microscopic theory for the generation and detection of coherent phonons in single-walled carbon nanotubes using a tight-binding model for the electronic states and a valence force field model for the phonons. We find that the coherent phonon amplitudes satisfy a driven oscillator equation with the driving term depending on photoexcited carrier density. We compared our theoretical results with experimental results on mod2 nanotubes and found that our model provides satisfactory overall trends in the relative strengths of the coherent phonon signal both within and between different mod2 families. We also find that the coherent phonon intensities are considerably weaker in mod1 nanotubes in comparison with mod2 nanotubes, which is also in excellent agreement with experiment.

Sanders, G. D.; Stanton, C. J.; Kim, J.-H.; Yee, K.-J.; Lim, Y.-S.; Hároz, E. H.; Booshehri, L. G.; Kono, J.; Saito, R.

2009-05-01

164

Effect of ozone oxidation on single-walled carbon nanotubes.  

PubMed

Exposing single-walled carbon nanotubes to room-temperature UV-generated ozone leads to an irreversible increase in their electrical resistance. We demonstrate that the increased resistance is due to ozone oxidation on the sidewalls of the nanotubes rather than at the end caps. Raman and X-ray photoelectron spectroscopies show an increase in the defect density due to the oxidation of the nanotubes. Using ultraviolet photoelectron spectroscopy, we show that these defects represent the removal of pi-conjugated electron states near the Fermi level, leading to the observed increase in electrical resistance. Oxidation of carbon nanotubes is an important first step in many chemical functionalization processes. Because the oxidation rate can be controlled with short exposures, UV-generated ozone offers the potential for use as a low-thermal-budget processing tool. PMID:16599473

Simmons, J M; Nichols, B M; Baker, S E; Marcus, Matthew S; Castellini, O M; Lee, C-S; Hamers, R J; Eriksson, M A

2006-04-13

165

Storage of hydrogen in single-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

Pores of molecular dimensions can adsorb large quantities of gases owing to the enhanced density of the adsorbed material inside the pores1, a consequence of the attractive potential of the pore walls. Pederson and Broughton have suggested2 that carbon nanotubes, which have diameters of typically a few nanometres, should be able to draw up liquids by capillarity, and this effect has been seen for low-surface-tension liquids in large-diameter, multi-walled nanotubes3. Here we show that a gas can condense to high density inside narrow, single-walled nanotubes (SWNTs). Temperature-programmed desorption spectrosocopy shows that hydrogen will condense inside SWNTs under conditions that do not induce adsorption within a standard mesoporous activated carbon. The very high hydrogen uptake in these materials suggests that they might be effective as a hydrogen-storage material for fuel-cell electric vehicles.

Dillon, A. C.; Jones, K. M.; Bekkedahl, T. A.; Kiang, C. H.; Bethune, D. S.; Heben, M. J.

1997-03-01

166

Oxidative Process for Cutting Single-Walled Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

Cut single-walled carbon nanotubes (SWNTs) are needed for many applications. An efficient way to produce bulk amounts of cut SWNTs is a two step process consisting of sidewall damage and oxidative exploitation. In these experiments sidewall damage is introduced by ozonation in a perfluoropolyether (PFPE) while monitoring the degree of functionalization with in-situ Raman spectroscopy. Use of PFPE allows for a high degree of sidewall functionalization at room temperature, mainly in the form of epoxides. These damaged SWNTs are exposed to piranha (4:1 96%H2SO4:H2O2) for one hour and then quenched. The piranha exposed samples are then functionalized with alkyl groups and spin cast on mica for length analysis. The cut samples are found to have significantly shorter lengths while maintaining a relatively high carbon yield.

Shaver, Jonah

2005-03-01

167

Surface oxidation study of single wall carbon nanotubes.  

PubMed

Functionalization of single wall carbon nanotubes (SWCNTs) is desirable to enhance their ability to be incorporated into polymers and enhance their bonding with the matrix. One approach to carbon nanotube functionalization is by oxidation via a strong oxidizing agent or refluxing in strong acids. However, this approach can damage the nanotubes, leading to the introduction of defects and/or shorter nanotubes. Such damage can adversely affect the mechanical, thermal, and electrical properties. A more benign approach to nanotube functionalization has been developed involving photo-oxidation. Chemical analysis by XPS revealed that the oxygen content of the photo-oxidized SWCNTs was 11.3 at.% compared to 6.7 at.% for SWCNTs oxidized by acid treatment. The photo-oxidized SWCNTs produced by this method can be used directly in various polymer matrices or can be further modified by additional chemical reactions. PMID:22020272

Lebrón-Colón, M; Meador, M A; Lukco, D; Solá, F; Santos-Pérez, J; McCorkle, L S

2011-10-21

168

Translocation events in a single-walled carbon nanotube  

NASA Astrophysics Data System (ADS)

Translocation of DNA oligomers through a single-walled carbon nanotube was demonstrated recently. Translocation events are accompanied by giant current pulses, the origin of which remains obscure. Here, we show that the introduction of a nucleotide, guanosine triphosphate, alone into the input reservoir of a carbon nanotube nanofluidic device also gives giant current pulses. Taken together with data on oligomer translocation, these new results suggest that the pulse width has a nonlinear, power-law dependence on the number of nucleotides in a DNA molecule. We have also measured the time for the onset of DNA translocation pulses after bias reversal, finding that the time for the onset of translocation is directly proportional to the period of the bias reversal.

He, Jin; Liu, Hao; Pang, Pei; Cao, Di; Lindsay, Stuart

2010-11-01

169

Stabilization and Carbonization of Gel Spun Polyacrylonitrile/Single Wall Carbon Nanotube Composite Fibers.  

National Technical Information Service (NTIS)

Gel spun polyacrylonitrile (PAN) and PAN/single wall carbon nanotube (SWNT) composite fibers have been stabilized in air and subsequently carbonized in argon at 1100 degrees C. Differential scanning calorimetry (DSC) and infrared spectroscopy suggests tha...

S. Kumar H. G. Chae M. Minus A. Rasheed

2007-01-01

170

Effects of artificial defects on the electrical transport of single-walled carbon nanotubes  

Microsoft Academic Search

We have investigated the effect of defects on the electrical transport properties of metallic single-walled carbon nanotubes (SWNTs). The defects are artificially induced by ion implantation and by deforming the SWNT with the SiO2 film deposited on it. Both defects are observed to act as gate-tunable electron scatters. With the dual gate structure, it is also shown that the scattering

J. W. Park; Jinhee Kim; J.-O. Lee; K. C. Kang; J.-J. Kim; K.-H. Yoo

2002-01-01

171

Anti-Stokes Raman spectra of single-walled carbon nanotubes  

Microsoft Academic Search

An analysis of the Stokes and anti-Stokes resonant Raman spectra of single-walled carbon nanotubes (SWNT's) using different laser energies in the range 1.49<=Elaser<=2.19 eV shows major differences in the tangential band spectra for the Stokes and anti-Stokes processes for selected Elaser values. These differences arise from the differences in the one-dimensional density of electronic states for metallic and semiconducting nanotubes.

S. D. M. Brown; P. Corio; A. Marucci; M. S. Dresselhaus; G. Dresselhaus; K. Kneipp

2000-01-01

172

Nonlinear characteristics of pseudo-Y-junction single-walled carbon nanotubes  

Microsoft Academic Search

We fabricated nanoscale field-effect transistors based on Y-junction single-walled carbon nanotubes (SWCNTs) and characterized their performance. The Y-junction transistor was modulated by a metallic branch of the Y-SWCNTs and exhibited the characteristics of an ambipolar field-effect transistor (FET) at room temperature. We obtained a subthreshold swing of 700 mV\\/decade and an Ion\\/off ratio of 105 with a low off-state leakage

Do-Hyun Kim; Jun Huang; Bangalore K. Rao; Wonbong Choi

2006-01-01

173

Fast electron beam-plasma interaction in single-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

A theoretical study on the plasmon-polariton modes coupled with a fast electron beam inside a metallic single-walled carbon nanotube is presented. The Maxwell's equations coupled with a linearized hydrodynamic model for the nanotube's charge oscillations are used. By considering the electron beam effects, general expression of dispersion relation of electromagnetic modes on nanotube's surface is obtained. It is shown numerically that by considering the electron beam effects, the polariton frequency shifts to lower values.

Moradi, Afshin

2013-04-01

174

Fabrication of single-walled carbon nanotubes dotted with Au nanocrystals: Potential DNA delivery nanocarriers  

Microsoft Academic Search

Single-walled carbon nanotubes (SWCNTs) dotted with Au nanocrystals (Au-SWCNTs) were fabricated by using a two-phase reduction of hydrogen tetrachloroaurate in the presence of thiol groups anchored to SWCNTs for their potential applications in DNA (deoxyribonucleic acid) delivery. To allow a surface reaction on SWCNTs during the metal nucleation and growth processes, Au nanocrystals were grown using a two-phase system. Raman,

Dae-Hwan Jung; Byung Hun Kim; Yong Taik Lim; Jaiwook Kim; Sang Yup Lee; Hee-Tae Jung

2010-01-01

175

Single-Walled Carbon Nanotubes as Shadow Masks for Nanogap Junction Fabrication  

NASA Astrophysics Data System (ADS)

We report a technique for fabricating nanometer-scale gaps in Pt wires on insulating substrates, using individual single-walled carbon nanotubes as shadow masks during metal deposition. 83% of the devices display current-voltage dependencies characteristic of direct electron tunneling. Fits to the current-voltage data yield gap widths in the 0.8 - 2.3 nm range for these devices, dimensions that are well suited for single-molecule transport measurements.

de Poortere, Etienne; Huang, Limin; Huang, Mingyuan; Wind, Shalom; Hone, James; O'Brien, Stephen; Stormer, Horst

2006-03-01

176

Single-walled carbon nanotubes as shadow masks for nanogap fabrication  

NASA Astrophysics Data System (ADS)

We describe a technique for fabricating nanometer-scale gaps in Pt wires on insulating substrates, using individual single-walled carbon nanotubes as shadow masks during metal deposition. More than 80% of the devices display current-voltage dependencies characteristic of direct electron tunneling. Fits to the current-voltage data yield gap widths in the 0.8-2.3 nm range for these devices, dimensions that are well suited for single-molecule transport measurements.

de Poortere, E. P.; Stormer, H. L.; Huang, L. M.; Wind, S. J.; O'Brien, S.; Huang, M.; Hone, J.

2006-04-01

177

Determination of moisture content of single-wall carbon nanotubes.  

PubMed

Several techniques were evaluated for the establishment of reliable water/moisture content of single-wall carbon nanotubes. Karl Fischer titration (KF) provides a direct measure of the water content and was used for benchmarking against results obtained by conventional oven drying, desiccation over anhydrous magnesium perchlorate as well as by thermogravimetry and prompt gamma-ray activation analysis. Agreement amongst results was satisfactory with the exception of thermogravimetry, although care must be taken with oven drying as it is possible to register mass gain after an initial moisture loss if prolonged drying time or elevated temperatures (120 °C) are used. Thermogravimetric data were precise but a bias was evident that could be accounted for by considering the non-selective loss of mass as volatile carbonaceous components. Simple drying over anhydrous magnesium perchlorate for a minimum period of 8-10 days is recommended if KF is not available for this measurement. PMID:22124752

Sturgeon, Ralph E; Lam, Joseph W; Windust, Anthony; Grinberg, Patricia; Zeisler, Rolf; Oflaz, Rabia; Paul, Rick L; Lang, Brian E; Fagan, Jeffrey A; Simard, Benoit; Kingston, Christopher T

2011-11-29

178

Raman modes of the deformed single-wall carbon nanotubes  

NASA Astrophysics Data System (ADS)

With the empirical bond polarizability model, the nonresonant Raman spectra of the chiral and achiral single-wall carbon nanotubes (SWCNTs) under uniaxial and torsional strains have been systematically studied by ab initio method. It is found that both the frequencies and the intensities of the low-frequency Raman-active modes almost do not change in the deformed nanotubes, while their high-frequency part shifts obviously. Especially, the high-frequency part shifts linearly with the uniaxial tensile strain, and two kinds of different shift slopes are found for any kind of SWCNTs. More interestingly, Raman peaks are found in the nonresonant Raman spectra under torsional strain, which are explained by (a) the symmetry breaking and (b) the effect of bond rotation and the anisotropy of the polarizability induced by bond stretching.

Wu, Gang; Zhou, Jian; Dong, Jinming

2005-09-01

179

Magnetic Fractionation and Alignment of Single Wall Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

We study mechanisms of single wall carbon nanotube (SWNT) alignment in a magnetic field. Through magnetic fractionation, we create SWNT suspensions with varying quantities of magnetic catalyst particles. The degree of tube alignment in magnetic fields up to 9 Tesla is quantified using polarized optical absorbance anisotropy. Continuous measurements of the nematic order parameter of these suspensions in variable magnetic fields provides a way to identify the origin of magnetic torques giving rise to nanotube alignment. Initial data suggests a transition from catalyst-driven to nanotube-anisotropy driven orientation as the catalyst fraction is reduced. We relate these results to observations of nanotube aggregation. This work has been supported by NSF through DMR-0203378, DMR-079909 and DGE-0221664, NASA through NAG8-2172, DARPA/ONR through N00014-01-1-0831, and SENS.

Islam, M. F.; Milkie, D. E.; Yodh, A. G.; Kikkawa, J. M.

2004-03-01

180

Ultra-short suspended single-wall carbon nanotube transistors  

NASA Astrophysics Data System (ADS)

We describe a method to fabricate clean suspended single-wall carbon nanotube (SWCNT) transistors hosting a single quantum dot ranging in length from a few 10 s of nm down to ~3 nm. We first align narrow gold bow-tie junctions on top of individual SWCNTs and suspend the devices. We then use a feedback-controlled electromigration to break the gold junctions and expose nm-sized sections of SWCNTs. We measure electron transport in these devices at low temperature and show that they form clean and tunable single-electron transistors. These ultra-short suspended transistors offer the prospect of studying THz oscillators with strong electron-vibron coupling.

Island, J. O.; Tayari, V.; Yi?en, S.; McRae, A. C.; Champagne, A. R.

2011-12-01

181

Polymer Dynamics in Single Wall Carbon Nanotube / Polystyrene Nanocomposites  

NASA Astrophysics Data System (ADS)

Polymer nanocomposites provide access to new regimes of polymer dynamics in which the impenetrable filler particles are comparable to and frequently smaller than the end-to-end distances of the polymer. In this study, single wall carbon nanotubes (SWCNTs) / polystyrene (PS) nanocomposite was prepared by a coagulation method. Rheological properties were measured in the linear viscoelastic regime and tracer diffusion coefficients were determined using an elastic recoil detection (ERD) method. The tracer diffusion coefficient first decreases and then increases with increasing SWCNT loading. Across this same range of filler concentration, the plateau modulus and the cross-over frequency are approximately constant. The transition from decreasing to increasing tracer diffusion corresponds approximately with the onset to rheological percolation and appears to increase with decreasing matrix molecular weight. A model is under development to describe the polymer dynamics is polymer nanocomposites.

Mu, Minfang; Composto, Russell; Clarke, Nigel; Winey, Karen

2008-03-01

182

Interaction of aromatic derivatives with single-walled carbon nanotubes.  

PubMed

Fluorescence of semiconducting single-walled carbon nanotubes (SWNTs) normally exhibits diameter-dependent oxidative quenching behaviour. This behaviour can be changed substantially to become an almost diameter-independent quenching phenomenon in the presence of electron-withdrawing nitroaromatic compounds, including o-nitrotoluene, 2,4-dinitrotoluene, and nitrobenzene. This change is observed for SWNTs suspended either in sodium dodecyl sulfate or in Nafion upon titration with hydrogen peroxide. Benzene, toluene, phenol, and nitromethane do not show such change. These findings suggest the possibility of forming an electron donor-acceptor complex between SWNTs and nitroaromatic compounds, resulting in leveling the redox potential of different SWNT species. The observation appears to provide a new method for modifying the electrochemical potentials of SWNTs through donor-acceptor complex formation. PMID:20878687

Hung, Wei-Chun; Elias, Gracy; Wai, Chien M

2010-11-15

183

Single-walled carbon nanotubes for high-performance electronics  

NASA Astrophysics Data System (ADS)

Single-walled carbon nanotubes (SWNT) could replace silicon in high-performance electronics with their exceptional electrical properties and intrinsic ultra-thin body. During the past five years, the major focus of this field is gradually shifting from proof-of-concept prototyping in academia to technology development in industry with emphasis on manufacturability and integration issues. This article reviews recent advances, starting with experimental and modeling works that evaluate the potential of adopting SWNTs in ultimately scaled transistors. Techniques to separate nanotubes according to their electronic types and assemble them into aligned arrays are then discussed, followed by a description of the engineering aspects in their implementation in integrated circuits and systems. A concluding discussion provides some perspectives on future challenges and research opportunities.

Cao, Qing; Han, Shu-Jen

2013-09-01

184

Selective bundling of zigzag single-walled carbon nanotubes.  

PubMed

A simple, high throughput fractionation procedure for aqueous/SDS (sodium dodecyl sulfate) suspensions of single-walled carbon nanotubes (SWNTs) is presented, which yields thin bundles of semiconducting-SWNTs with small chiral angles. To demonstrate this we show the photoluminescence signatures of nanotube suspensions that contain almost exclusively zigzag and near-zigzag tubes. Starting suspensions and resulting fractions were characterized using optical absorption, resonance Raman and photoluminescence spectroscopies as well as scanning force microscopy. Taken together with literature observations, our findings suggest that near zigzag edge tubes of similar diameters in a bundle are harder to separate from each other than for other chiral index combinations. We discuss the implications of these observations for SWNT growth and dispersion. PMID:21410134

Blum, Carolin; Stürzl, Ninette; Hennrich, Frank; Lebedkin, Sergei; Heeg, Sebastian; Dumlich, Heiko; Reich, Stephanie; Kappes, Manfred M

2011-03-23

185

Connection of Single-Walled Carbon Nanotubes by Bandaging with a Bigger Radius Single-Walled Carbon Nanotube  

NASA Astrophysics Data System (ADS)

We report molecular dynamics studies of single-walled carbon nanotubes (SWCNT) as a bandage to connect separated SWCNTs for getting structures of random length. The mechanical properties of the connected SWCNT strands with different joint length under axial loads are investigated using the classical molecular dynamics simulations method. The interaction between atoms is modeled using the second-generation of reactive empirical bond-order (REBO) potential coupled with the Lennard-Jones (L-J) potential. The mechanical properties, such as Young's modulus, tensile strength, critical buckling strains and critical buckling loads are determined and presented for SWCNT and connected SWCNT strands. The results indicates that the joints made in this way have relatively high mechanical properties corresponding to that of the ideal SWCNTs.

Song, Hai-Yang; Hu, Ming-Liang; Zha, Xin-Wei

186

Cutting of single-walled carbon nanotubes by ozonolysis.  

PubMed

Cutting of single-walled carbon nanotubes (SWNT) has been achieved by extensive ozonolysis at room temperature. Perfluoropolyether (PFPE) was selected as a medium for cutting SWNT due to its high solubility for ozone (O3). A mixture of 9 wt % of O3 in O2 was bubbled through a homogeneous suspension of pristine SWNT in PFPE, at room temperature. The intense disorder mode in the Raman spectra of ozonated SWNT indicates that extensive reaction with the sidewalls of SWNT occurs during ozonolysis. Atomic force microscopy (AFM) images of SWNT, before and after ozonolysis, provided a measure of the extent of the cutting effects. Monitoring of the evolved gases for both pristine and purified SWNT indicates CO2 was produced during the ozonolysis process with a dependence on both system pressure and temperature. During heating, FTIR analysis of gases released indicated that carbon oxygen groups on the sidewalls of SWNT are released as CO2. SWNT was found to be extensively cut after an ozone treatment with a yield of approximately 80% of the original carbon. PMID:16800455

Chen, Zheyi; Ziegler, Kirk J; Shaver, Jonah; Hauge, Robert H; Smalley, Richard E

2006-06-22

187

Interactions between single-walled carbon nanotubes and lysozyme.  

PubMed

Dispersions of single-walled and non-associated carbon nanotubes in aqueous lysozyme solution were investigated by analyzing the stabilizing effect of both protein concentration and pH. It was inferred that the medium pH, which significantly modifies the protein net charge and (presumably) conformation, modulates the mutual interactions with carbon nanotubes. At fixed pH, in addition, the formation of protein/nanotube complexes scales with increasing lysozyme concentration. Electrophoretic mobility, dielectric relaxation and circular dichroism were used to determine the above features. According to circular dichroism, lysozyme adsorbed onto nanotubes could essentially retain its native conformation, but the significant amount of free protein does not allow drawing definitive conclusions on this regard. The state of charge and charge distribution around nanotubes was inferred by combining electrophoretic mobility and dielectric relaxation methods. The former gives information on changes in the surface charge density of the complexes, the latter on modifications in the electrical double layer thickness around them. Such results are complementary each other and univocally indicate that some LYS molecules take part to binding. Above a critical protein/nanotube mass ratio, depletion phenomena were observed. They counteract the stabilization mechanism, with subsequent nanotube/nanotube aggregation and phase separation. Protein-based depletion phenomena are similar to formerly reported effects, observed in aqueous surfactant systems containing carbon nanotubes. PMID:21215413

Bomboi, F; Bonincontro, A; La Mesa, C; Tardani, F

2010-12-15

188

Photophysics of polymer-wrapped single-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

Single-walled carbon nanotubes (SWNTs) are successfully dispersed in two conjugated polymer poly(9,9-dioctylfluorenyl-2,7-diyl) (PFO) and poly[2-methoxy-5- (2’-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEHPPV) solutions. Steady-state and time-resolved photoluminescence spectroscopy in the near-infrared and visible spectral regions are used to study the interaction of the dispersed carbon nanotube and the wrapped polymer in the nano-hybrids. The SWNTs infrared emission is the signatures of the separation of single semiconducting tubes, the lifetime of the photoluminescence of these tubes is bi-exponential with the first component varying from 6 ps (in MEHPPV wrapped SWNTs) to 14 ps (in PFO wrapped SWNTs), while the second component of the decay for all samples is in the range of 30-40 ps, revealing the intrinsic lifetime of the SWNTs. The study of the photoluminescence of the nano-hybrids in the visible spectral range shows, in the case of the PFO, a relatively strong quenching, the photoluminescence lifetime for the hybrid is more than 100 ps shorter than the one of the pristine polyfluorene solution. For the MEHPPV-SWNT hybrid an opposite behavior is revealed with the photoluminescence lifetime surprisingly longer than the polymer solution. The possible mechanism for the interaction of the two conjugated polymers and the SWNTs is discussed in terms of their electronic band structure.

Gao, J.; Loi, M. A.

2010-05-01

189

Transversely isotropic elastic properties of single-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

While it is known that the elastic properties of a single-walled carbon nanotube (SWNT) are transversely isotropic, the closed-form solutions for all five independent elastic moduli have not been solved completely. In this paper, an energy approach in the framework of molecular mechanics is used to evaluate the local and global deformations of a SWNT in a unified manner. This is carried out under four loading conditions: axial tension, torsional moment, in-plane biaxial tension, and in-plane pure shear, respectively, from which the closed-form expressions for the longitudinal Young’s modulus, major Poisson’s ratio, longitudinal shear, plane strain bulk, and in-plane shear moduli are obtained. It is shown that as the tube diameter increases, the major Poisson’s ratio approaches a constant, the longitudinal Young’s and shear moduli and the plane strain bulk modulus are inversely proportional to the tube diameter, and the in-plane shear modulus is inversely proportional to the third power of the tube diameter. The dependence of the elastic moduli of a SWNT on the tube diameter and helicity is displayed and discussed.

Shen, Lianxi; Li, Jackie

2004-01-01

190

Hypergolic fuel detection using individual single walled carbon nanotube networks  

SciTech Connect

Accurate and reliable detection of hypergolic fuels such as hydrazine (N{sub 2}H{sub 4}) and its derivatives is vital to missile defense, aviation, homeland security, and the chemical industry. More importantly these sensors need to be capable of operation at low temperatures (below room temperature) as most of the widely used chemical sensors operate at high temperatures (above 300 deg. C). In this research a simple and highly sensitive single walled carbon nanotube (SWNT) network sensor was developed for real time monitoring of hydrazine leaks to concentrations at parts per million levels. Upon exposure to hydrazine vapor, the resistance of the air exposed nanotubes (p-type) is observed to increase rapidly while that of the vacuum-degassed nanotubes (n-type) is observed to decrease. It was found that the resistance of the sample can be recovered through vacuum pumping and exposure to ultraviolet light. The experimental results support the electrochemical charge transfer mechanism between the oxygen redox couple of the ambient and the Fermi level of the SWNT. Theoretical results of the hydrazine-SWNT interaction are compared with the experimental observations. It was found that a monolayer of water molecules on the SWNT is necessary to induce strong interactions between hydrazine and the SWNT by way of introducing new occupied states near the bottom of the conduction band of the SWNT.

Desai, S. C.; Willitsford, A. H. [Department of Electrical and Computer Engineering, University of Louisville, Louisville, Kentucky 40292 (United States); Sumanasekera, G. U. [Department of Electrical and Computer Engineering, University of Louisville, Louisville, Kentucky 40292 (United States); Department of Physics and Astronomy, University of Louisville, Louisville, Kentucky 40292 (United States); Yu, M.; Jayanthi, C. S.; Wu, S. Y. [Department of Physics and Astronomy, University of Louisville, Louisville, Kentucky 40292 (United States); Tian, W. Q. [State Key Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun 130023 (China)

2010-06-15

191

Optical properties of assembled single-walled carbon nanotube gels.  

PubMed

A macroscopic system of single-walled carbon nanotubes (SWNTs) created by a novel DNA/protein complex-assisted assembly is investigated. Due to a point-like nature of connectors, the resulting SWNT aerogel represents a network of self-suspended nanotubes with a record-low density of less than 0.75 mg cm(-3). The assembly method and low density enable a direct comparison of optical properties of nanotubes in solvent and air to surfactant solubilized nanotubes. Optical properties of SWNT gels are investigated using optical absorption, photoluminescence, and Raman spectroscopy. Gelled nanotubes in water and in the low-energy regime behave similar to solubilized nanotubes. In contrast, the photoluminescence of SWNT aerogels exhibits a previously unobserved peak at 1.3 eV that corresponds to a phonon-assisted recombination of photoexcited charges. This new emission pathway is the result of the unique nature of self-suspended nanotubes in aerogel and a reduced phonon decay. PMID:22461220

Ostojic, Gordana N

2012-03-27

192

Oxygen-Assisted Synthesis of Single-Walled Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

Water-assisted chemical vapor deposition (CVD) has become a standard synthesis method for high quality single-walled carbon nanotubes (SWCNTs). Some drawbacks of the water-assisted method, however, include good control of water concentrations in the feedstock and poor control of SWCNT diameters below 2.0 nm. Here, we describe a variation of water-assisted CVD that uses dry feedstocks with a small, controlled quantity of molecular oxygen. Reactions of oxygen with hydrogen in the reaction zone provide all the benefits of water-assisted growth at the substrate while maintaining dry valves and flowmeters. In addition, the oxygen-based technique allows water concentrations in the system to be varied precisely and with short time constants. Perhaps because of the improved control, we find that the SWCNT diameter can be easily tuned by changing the oxygen concentration during the growth phase. Changing the oxygen concentration over the range of 0.5% to 1% varied the resulting SWCNT diameters from 1.5 to 0.5 nm, with typical diameter distributions less than +/- 30%. Control of SWCNT growth within this diameter range is ideal for probing opto-electronic properties of individual SWCNTs and SWCNT devices.

Tolga Gul, O.; Rajapakse, Arith J.; Collins, Philip G.

2013-03-01

193

Bulk Mechanical Properties of Single Walled Carbon Nanotube Electrodes  

NASA Astrophysics Data System (ADS)

The unique properties of single walled carbon nanotubes (SWNTs) make them especially well suited for use as electrodes in power devices such as lithium ion batteries, hydrogen fuel cells, solar cells, and supercapacitors. The performances of such devices are expected to be influenced, at least in part, by the mechanical properties of the SWNTs used in composites or in stand alone ``papers.'' Therefore, the elastic moduli and ultimate tensile strengths of SWNT papers were measured as functions of temperature, SWNT purity, SWNT length, and SWNT bundling. The SWNTs used to produce the papers were synthesized in an alexandrite laser vaporization reactor at 1100^oC and purified using conventional acid-reflux conditions. Characterization of the SWNTs was performed using SEM, BET, TGA, and optical and Raman spectroscopy. The purified material was filtered and dried to yield papers of bundled SWNTs which were analyzed using dynamic mechanical analysis (DMA). It was observed that the mechanical properties of acid-refluxed SWNT papers were significantly improved by controlled thermal oxidation and strain-hardening. Elastic moduli of SWNT papers were measured between 3 and 6 GPa. Ultimate (breaking) tensile stresses were measured between 45 and 90 MPa at 1-3% strain. These results and their implications in regard to potential applications in power devices will be discussed.

Giarra, Matthew; Landi, Brian; Cress, Cory; Raffaelle, Ryne

2007-03-01

194

Raman Spectroscopy of Single Wall Carbon Nanotubes Upon Electrochemical Doping  

NASA Astrophysics Data System (ADS)

Single wall carbon nanotubes in vacuum filtered papers were studied using Raman scattering. Spectra of the tangential displacement modes (TDM: ˜1580cm-1) and radial breathing modes (RBM: ˜200cm-1) were measured at several excitation wavelengths between 476.5nm and 676.4nm, and the mean diameter and diameter distribution of the tubes were determined from theoretical predictions of the RBM frequencies. The effects of electrochemical doping on the Raman spectra of the tubes were studied in 1M and 5M solutions of NaCl at applied biases of -2V to 2 V. Under resonance conditions (near 647.1nm excitation) we found that the scattered intensities of the RBM decrease linearly and the TDM frequencies shift with increasing voltage. Both effects are reversible upon de-doping in the stated voltage range. Irreversible effects, however, are seen to occur when higher voltages (>2V) are applied, indicating a deep absorption of dopant ions into the nanotube lattice or permanent damage to the tubes themselves.

Kennedy, W. Joshua; Vardeny, Valy; Dalton, Alan; Baughman, Ray; Munoz, Edgar; Zakhidov, Anvar

2002-10-01

195

Microwave Conductivity of Single Wall Carbon Nanotube Arrays  

NASA Astrophysics Data System (ADS)

We have developed a coplanar waveguide (CPW) platform compatible with both broadband (0.01 to 50 GHz) microwave scattering parameter measurements and directed assembly of carbon nanotubes (CNTs) and semiconductor nanowires. Utilizing AC dielectrophoresis and lithographic masking techniques, single-wall CNTs prepared with single-stranded DNA as a surfactant were assembled in localized parallel arrays between CPW signal and ground electrodes. This places the CNTs parallel to the electric field in the propagating region where coupling to the CNT conductivity alters the impedance of the CPW. The conductivity of the CNT arrays is deduced from scattering parameter measurements before and after assembly of the CNTs. Preliminary measurements show that at least some types of CNT material have a small but definite high-frequency loss that increases with frequency. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Highstrete, C.; Lee, Mark; Shaner, E. A.; Jones, F. E.; Talin, A. A.; Robinson, D. B.; Dentinger, P. M.

2006-03-01

196

Design Criteria for Transparent Single-Wall Carbon Nanotube Thin-Film Transistors  

Microsoft Academic Search

ABSTRACT A study,based,on two-dimensional,percolation theory yielding quantitative parameters,for optimum,connectivity of transparent,single-wall carbon nanotube,(SWNT) thin films is reported. Optimum,SWNT concentration,in the filtrated solution was,found to be 0.1 mg\\/L with a volume of 30 mL. Such parameters l,. Therefore, the performance of transparent carbon nanotube thin-film transistors is limited by the metallic SWNTs, even below their percolation threshold. We show how this

Husnu Emrah Unalan; Giovanni Fanchini; Alokik P. Kanwal; Aurelien Du Pasquier; Manish Chhowalla

2006-01-01

197

Electronic Durability of Flexible Transparent Films from Type-Specific Single-Wall Carbon Nanotubes  

SciTech Connect

The coupling between mechanical flexibility and electronic performance is evaluated for thin films of metallic and semiconducting single-wall carbon nanotubes (SWCNTs) deposited on compliant supports. Percolated networks of type-purified SWCNTs are assembled as thin conducting coatings on elastic polymer substrates, and the sheet resistance is measured as a function of compression and cyclic strain through impedance spectroscopy. The wrinkling topography, microstructure and transparency of the films are independently characterized using optical microscopy, electron microscopy, and optical absorption spectroscopy. Thin films made from metallic SWCNTs show better durability as flexible transparent conductive coatings, which we attribute to a combination of superior mechanical performance and higher interfacial conductivity.

Harris, J; Iyer, S; Bernhardt, A; Huh, JY; Hudson, S; Fagan, J; Hobbie, E.

2011-12-11

198

Donor doping of single-walled carbon nanotubes by filling of channels with silver  

SciTech Connect

The channels of single-walled carbon nanotubes (SWNTs) are filled with metallic silver. The synthesized nanocomposites are studied by Raman spectroscopy and optical absorption spectroscopy, and these data indicate a substantial modification of the electronic structure of the nanotubes upon their filling. Moreover, X-ray photoelectron spectroscopy shows that the incorporation of the metal leads to a change in the work function of SWNTs due to the Fermi level upshift and to the transfer of an electron density from inserted nanoparticles to the nanotube walls. Thus, the filling of the channels with silver results in donor doping of the nanotubes.

Kharlamova, M. V., E-mail: mv.kharlamova@gmail.com [Moscow State University (Russian Federation); Niu, J. J. [Drexel University, Department of Materials Science and Engineering (United States)

2012-09-15

199

Unusually large Franz-Keldysh oscillations at ultraviolet wavelengths in single-walled carbon nanotubes.  

PubMed

We report large electroabsorption susceptibilities in the ultraviolet region for single-walled carbon nanotubes (SWNT) supported on quartz that are approximately 10;{3} larger than the highest values reported to date for any system. The oscillatory behavior is described using a convolution of Airy functions in photon energy ascribing the effect to Franz-Keldysh oscillations. The metallic and semiconducting SWNT composition is varied, and it is shown that the confinement energy correlates with the average band gap for semiconducting SWNT in the film. The large susceptibilities arise from a subpercolated network of metallic SWNT that enhances the local electric field. PMID:19257475

Ham, Moon-Ho; Kong, Byung-Seon; Kim, Woo-Jae; Jung, Hee-Tae; Strano, Michael S

2009-01-30

200

Nano-electromechanical displacement sensing based on single-walled carbon nanotubes.  

PubMed

We present a nano-electromechanical system based on an individual single-walled carbon nanotube (SWNT) demonstrating their potential use for future displacement sensing at the nanoscale. The fabrication and characterization of the proposed nanoscaled transducer, consisting of a suspended metal cantilever mounted on top of the center of a suspended SWNT, is presented and discussed. The displacement of the nanoscale cantilever is detected via the electromechanically induced change in conductance of the strained SWNT. A relative differential resistance sensitivity (for a metallic SWNT) of up to 27.5%/nm was measured and a piezoresistive gauge factor of a SWNT of up to 2900 was extracted. PMID:16834427

Stampfer, C; Jungen, A; Linderman, R; Obergfell, D; Roth, S; Hierold, C

2006-07-01

201

Direct Synthesis of Long Single-Walled Carbon Nanotube Strands  

NASA Astrophysics Data System (ADS)

In the processes that are used to produce single-walled nanotubes (electric arc, laser ablation, and chemical vapor deposition), the typical lengths of tangled nanotube bundles reach several tens of micrometers. We report that long nanotube strands, up to several centimeters in length, consisting of aligned single-walled nanotubes can be synthesized by the catalytic pyrolysis of n-hexane with an enhanced vertical floating technique. The long strands of nanotubes assemble continuously from arrays of nanotubes, which are intrinsically long.

Zhu, H. W.; Xu, C. L.; Wu, D. H.; Wei, B. Q.; Vajtai, R.; Ajayan, P. M.

2002-05-01

202

Theoretical study of the interactions of carbon monoxide with Rh-decorated (8,0) single-walled carbon nanotubes  

Microsoft Academic Search

Recent laboratory studies have shown that metal nanoparticles-decorated single-walled carbon nanotubes (SWCNTs) can be used to detect carbon monoxide (CO) gases at room temperature, which is known not able to be adsorbed on pure SWCNTs. In this paper, we investigated the Rh-decorated (8,0) SWCNT and its interaction with CO gases by using density functional theory (DFT) methods. Upon Rh atom

Jing-Xiang Zhao; Yi-Hong Ding

2008-01-01

203

Giant cationic polyelectrolytes generated via electrochemical oxidation of single-walled carbon nanotubes.  

PubMed

Previously, reduced single-walled carbon nanotube anions have been used for effective processing and functionalization. Here we report individually separate and distinct (that is, discrete) single-walled carbon nanotube cations, directly generated from a pure anode using a non-aqueous electrochemical technique. Cyclic voltammetry provides evidence for the reversibility of this nanoion electrochemisty, and can be related to the complex electronic density of states of the single-walled carbon nanotubes. Fixed potentiostatic oxidation allows spontaneous dissolution of nanotube cations ('nanotubium'); Raman spectroscopy and transmission electron microscopy show that sequential fractions are purified, separating amorphous carbon and short, defective single-walled carbon nanotubes, initially. The preparation of nanotubium, in principle, enables a new family of nucleophilic grafting reactions for single-walled carbon nanotubes, exploited here, to assemble nanotubes on amine-modified Si surfaces. Other nanoparticle polyelectrolyte cations may be anticipated. PMID:23764646

Hodge, Stephen A; Bayazit, Mustafa K; Tay, Hui Huang; Shaffer, Milo S P

2013-01-01

204

Synthesis, assembly, and applications of single-walled carbon nanotube  

Microsoft Academic Search

This dissertation presents the synthesis and assembly of aligned carbon nanotubes, and their applications in both nano-electronics such as transistor and integrated circuits and macro-electronics in energy conversion devices as transparent conducting electrodes. Also, the high performance chemical sensor using metal oxide nanowire has been demonstrated. Chapter 1 presents a brief introduction of carbon nanotube, followed by discussion of a

Koungmin Ryu

2009-01-01

205

Effects of single-walled carbon nanotubes on soil microorganisms  

NASA Astrophysics Data System (ADS)

Single-walled carbon nanotubes (SWCNTs) are novel materials that have the potential to be used in various commercial fields due to their unique physicochemical properties. As a result of commercial development of nanotechnology, SWCNTs may be discharged to the soil environment with unknown consequences. However, there are as yet no data in the scientific literature that demonstrate the effects of SWCNTs on microbial function in soils. Therefore, we aimed to determine the effects of SWCNTs on soil microbial activity through a 2-week incubation study on urban soils supplemented with different concentrations of SWCNTs ranging from 0 to 1000 ?g CNT/g soil. Fluorometric test using fluorogenic substrates were employed for the measurement of several enzyme activities in soil samples. More specifically, we determined the changes in the activities of cellobiohydrolase, ?-1,4-glucosidase, ?-1,4-xylosidase, ?-1,4-N-acetylglucosaminidase, L-leucine aminopeptidase and acid phosphatase which play important roles in the carbon, nitrogen, and phosphorus cycles in response to the addition of SWCNTs. We found that microbial enzyme activities decreased as the concentrations of SWCNT added increased. The lowest enzyme activities were observed under 1000 ?g CNT/g soil. The overall pattern shows that enzyme activities decreased slightly in the first 2-3 days and increased in the later stage of the incubation. Our results suggest that relatively high concentrations of SWCNTs can inhibit microbial activities, and this may be due to microbial cell membrane damage caused by SWCNTs. However, further study needs to be conducted to determine the mechanism responsible for inhibitory effect of SWCNTs on soil microbial activity. It can be concluded that changes in the activities of extracellular enzymes can indicate the effect of SWCNTs on soil microorganisms and nutrient cycling.

Jin, L.; Chung, H.; Son, Y.

2011-12-01

206

Radiation effects in single-walled carbon nanotube papers  

SciTech Connect

The effects of ionizing radiation on the temperature-dependent conductivity of single-walled carbon nanotube (SWCNT) papers have been investigated in situ in a high vacuum environment. Irradiation of the SWCNT papers with 4.2 MeV alpha particles results in a steady decrease in the SWCNT paper conductivity, resulting in a 25% reduction in room temperature conductivity after a fluence of 3x10{sup 12} alpha particles/cm{sup 2}. The radiation-induced temperature-dependent conductivity modification indicates that radiation damage causes an increase in the effective activation barrier for tunneling-like conductivity and a concomitant increase in wavefunction localization of charge carriers within individual SWCNTs. The spatial defect generation within the SWCNT paper was modeled and confirms that a uniform displacement damage dose was imparted to the paper. This allows the damage coefficient (i.e., differential change in conductivity with fluence) for alpha particles, carbon ions, and protons to be compared with the corresponding nonionizing energy loss (NIEL) of the incident particle. The resulting nonlinear relationship with NIEL between these parameters is distinct from the more typical linear response observed in many bulk semiconductors and superconductors and indicates that localized radiation damage in the SWCNT papers has a greater impact than distributed damage. Although SWCNT papers behave largely as a bulk material with properties that are a convolution of the underlying SWCNT distribution, the radiation response appears to be largely dominated by degradation in the preferred one-dimensional conduction within these two-dimensionally confined nanostructures.

Cress, Cory D.; Messenger, Scott R.; Walters, Robert J. [Electronics Science and Technology Division, U.S. Naval Research Laboratory, Washington, DC 20375 (United States); Schauerman, Christopher M.; Raffaelle, Ryne P. [NanoPower Research Laboratories, Rochester Institute of Technology, Rochester, New York 14623 (United States); Landi, Brian J. [NanoPower Research Laboratories, Rochester Institute of Technology, Rochester, New York 14623 (United States); Department of Chemical and Biomedical Engineering, Rochester Institute of Technology, Rochester, New York 14623 (United States)

2010-01-15

207

Noncovalent functionalization of single-walled carbon nanotubes with porphyrins  

NASA Astrophysics Data System (ADS)

The covalent and noncovalent interactions of porphyrins and related tetraazamacrocyclic compounds with single-walled carbon nanotubes (SWNTs) is a subject of increasing research effort, directed toward the design of novel hybrid nanomaterials combining unique electronic and optical properties of both molecular species. In this report, we used different experimental techniques as well as molecular mechanics (MM) calculations to analyze the adsorption of meso-tetraphenylporphine (or 5,10,15,20-tetraphenyl-21H,23H-porphine, H2TPP) and its complexes with Ni(II) and Co(II) (NiTPP and CoTPP, respectively), as well as hemin (a natural porphyrin), onto the surface of SWNTs. Altogether, the results suggested that all four porphyrin species noncovalently interact with SWNTs, forming hybrid nanomaterials. Nevertheless, of all four porphyrin species, the strongest interaction with SWNTs occurs in the case of CoTPP, which is able to intercalate and considerably disperse SWNT bundles, and therefore absorb onto the surface of individual SWNTs. In contrast, NiTPP, CoTPP and hemin, due to a weaker interaction, are unable to do so and therefore are only capable to adsorb onto the surface of SWNT bundles. According to the scanning tunneling microscopy (STM) imaging and MM results, the adsorption of CoTPP onto SWNT sidewalls results in the formation of porphyrin arrays in the shape of long-period interacting helixes with variable periodicity, possibly due to different diameters and chiralities of SWNTs present in the samples. Since the remaining porphyrin species were found to adsorb onto the surface of SWNT bundles, the precise geometry of the corresponding porphyrin/SWNT complexes is difficult to characterize.

Bassiouk, María; Basiuk, Vladimir A.; Basiuk, Elena V.; Álvarez-Zauco, Edgar; Martínez-Herrera, Melchor; Rojas-Aguilar, Aaron; Puente-Lee, Iván

2013-06-01

208

Single-walled carbon nanotube-silicon nitride composites  

NASA Astrophysics Data System (ADS)

Colloidal processing methods were developed in order to disperse highly concentrated 1.0, 2.0, and 6.0 vol% single-walled carbon nantoube (SWNT)-Si 3N4 aqueous composite suspensions. Interparticle pair potentials were developed between individual Si3N4 particles and SWNT bundles by coating them with cationic surfactant molecules of cetyltrimethylammonium bromide (CTAB). Zeta potential, viscosity, and sedimentation measurements were conducted on SWNTs and Si3N4 particle suspensions in order to optimize the pH and amount of adsorbed CTAB. The composite suspension viscosity was pH sensitive and adjusted accordingly before consolidation into three-dimensional solid parts using a rapid prototyping fabrication method called robocasting. High-density composites were produced using spark plasma sintering and structurally intact SWNTs were directly observed in the final sintered microstructure using scanning electron microscopy and Raman spectroscopy. When processed with SWNTs the highly insulative ceramic became electrically conductive and resulted in increased grindability for the otherwise hard to machine ceramic. The high hardness, fracture toughness and density of Si 3N4 was maintained for the composite due to the detailed development of colloidal processing and sintering methods used during fabrication. In addition, the thermal conductivity of the ceramic was reduced with the incorporation of well-dispersed SWNTs. Indentation load studies on the composites revealed sub-surface chipping and deformation around the indent before radial crack development indicating a degree of damage tolerance over the monolith. Along the wake of the crack SWNTs were also observed bridging the crack therefore showing their potential to act as toughening agents in brittle ceramics.

Corral, Erica Lorrane

209

Nano-Plasticity of Single-Wall Carbon Nanotubes Under Uniaxial Compression.  

National Technical Information Service (NTIS)

Nano-plasticity of thin single-wall carbon nanotubes under uniaxial compression is investigated through generalized tight-binding molecular dynamics (GTBMD) and ab-initio electronic structure methods. A novel mechanism of nano-plasticity of carbon nanotub...

D. Srivastava M. Menon K. Cho

1999-01-01

210

Synthesis of Single-Walled Carbon Nanotubes in a Glow Discharge Fine Particle Plasma  

SciTech Connect

Carbon fine particles were synthesized being negatively charged and confined in a glow discharge plasma. The deposited fine particles were analyzed by Raman spectroscopy and transmission electron microscopy (TEM) and were confirmed to include single-walled carbon nanotubes.

Imazato, N.; Imano, M.; Hayashi, Y. [Kyoto Institute of Technology, Sakyo-ku, Kyoto 606-8585 (Japan)

2008-09-07

211

Characterization of Isolated Individual Single-Walled Carbon Nanotube by Electrochemical Scanning Tunneling Microscopy  

NASA Astrophysics Data System (ADS)

The local density of states (LDOS) of an isolated single-walled carbon nanotube (SWNT) was characterized by electrochemical scanning tunneling microscopy and spectroscopy (EC-STM and EC-STS). Discrimination of individual semiconducting and metallic nanotubes adsorbed on a Au(111) surface was demonstrated by analyzing EC-STS spectra under electrochemical control at a nanometer scale. Two distinct LDOS determined from differential EC-STS spectra are found to be characteristic of the conduction and valence bands, corresponding to van Hove singularities of the SWNT. The absolute potential of the energy level and the band gap between these bands for semiconducting nanotubes could be also evaluated.

Yasuda, Satoshi; Ikeda, Kouta; Yu, Li; Murakoshi, Kei

2012-08-01

212

Controlling the doping of single-walled carbon nanotube networks by proton irradiation  

SciTech Connect

We demonstrate the controlled desorption of adventitious dopants on networks of single-walled carbon nanotubes (SWNTs) with 100 keV proton irradiation. Networks of sorted metallic, semiconducting SWNTs, and unsorted SWNTs were investigated. The removal of dopants was indicated by an increase in sheet resistances along with an increase in the absorption of the low energy absorption band of semiconducting SWNTs. Semiconducting and unsorted SWNT networks exhibited the largest change in their sheet resistance, which indicates the conductivity of unsorted SWNT networks is dominated by the tube-tube junctions of semiconducting SWNTs.

Walker, D.; Mann, C. J.; Panetta, C. J.; Alaan, D. R.; Hopkins, A. R.; Liu, S. H. [Physical Sciences Laboratories, Aerospace Corporation, P. O. Box 92957 M2/275, Los Angeles, California 90009-2957 (United States)

2012-09-03

213

Increasing the length of single-wall carbon nanotubes in a magnetically enhanced arc discharge  

SciTech Connect

It is demonstrated that a magnetic field has a profound effect on the length of a single-wall carbon nanotube (SWCNT) synthesized in the arc discharge. The average length of SWCNT increases by a factor of 2 in discharge with magnetic field as compared with the discharge without magnetic field, and the yield of long nanotubes with lengths above 5 {mu}m also increases. A model of SWCNT growth on metal catalyst in arc plasma was developed. Monte-Carlo simulations confirm that the increase of the plasma density in the magnetic field leads to an increase in the nanotube growth rate and thus leads to longer nanotubes.

Keidar, Michael [Department of Mechanical and Aerospace Engineering, George Washington University, Washington, District of Columbia 20052 (United States); Levchenko, Igor; Ostrikov, Kostya [Plasma Nanoscience, School of Physics, The University of Sydney, Sydney, New South Wales 2006 (Australia); Arbel, Tamir [Department of Material Science, University of Michigan, Ann Arbor, Michigan 48109 (United States); Alexander, Myriam [Department of Geophysical Science, University of Chicago, Chicago, Illinois 60637 (United States); Waas, Anthony M. [Department of Aerospace Engineering, University of Michigan, Ann Arbor, Michigan 48109 (United States)

2008-01-28

214

Electronic properties of mechanically induced kinks in single-walled carbon nanotubes  

SciTech Connect

We have used an atomic-force microscope tip to mechanically buckle single-walled carbon nanotubes. The resistance of the induced defects ranged from 10 to 100 k{Omega} and varied with the local Fermi level, as determined by scanned-gate microscopy. By forming two closely spaced defects on metallic nanotubes, we defined quantum dots less than 100 nm in length. These devices exhibited single-electron charging behavior at temperatures up to {similar_to}165 K. {copyright} 2001 American Institute of Physics.

Bozovic, Dolores; Bockrath, M.; Hafner, Jason H.; Lieber, Charles M.; Park, Hongkun; Tinkham, M.

2001-06-04

215

Diameter Control of Single-Wall Carbon Nanotubes by the Catalytic Chemical Vapor Deposition Method  

NASA Astrophysics Data System (ADS)

Single-walled carbon nanotubes (SWNTs) have been synthesized by the pyrolysis of acetylene over well-dispersed metal particles (cobalt and iron) embedded on catalyst supports such as commercially available zeolites and in-house mesoporous silica at temperature above 800°C. Pristine specimens produced with different catalyst supports are characterized by transmission electron microscopy and Raman spectroscopy. It is found that some SWNTs in the pristine soot have a diameter distribution nearly equivalent to the surface pore size of the each catalyst supports.

Okamoto, A.; Kawakubo, T.; Hiraoka, T.; Okazaki, T.; Sugai, T.; Shinohara, H.

2002-10-01

216

Deformation of Doubly Clamped Single-Walled Carbon Nanotubes in an Electrostatic Field  

NASA Astrophysics Data System (ADS)

In this Letter, we demonstrate a strong dependence of the electrostatic deformation of doubly clamped single-walled carbon nanotubes on both the field strength and the tube length, using molecular simulations. Metallic nanotubes are found to be more sensitive to an electric field than semiconducting ones of the same size. For a given electric field, the induced deformation increases with tube length but decreases with tube radius. Furthermore, it is found that nanotubes can be more efficiently bent in a center-oriented transverse electric field.

Wang, Zhao; Philippe, Laetitia

2009-05-01

217

Energy loss of the electron system in individual single-walled carbon nanotubes.  

PubMed

We characterize the energy loss of the nonequilibrium electron system in individual metallic single-walled carbon nanotubes at low temperature. Using Johnson noise thermometry, we demonstrate that, for a nanotube with Ohmic contacts, the dc resistance at finite bias current directly reflects the average electron temperature. This enables a straightforward determination of the thermal conductance associated with cooling of the nanotube electron system. In analyzing the temperature- and length-dependence of the thermal conductance, we consider contributions from acoustic phonon emission, optical phonon emission, and hot electron outdiffusion. PMID:20931994

Santavicca, Daniel F; Chudow, Joel D; Prober, Daniel E; Purewal, Meninder S; Kim, Philip

2010-10-08

218

Different techniques for characterizing single-walled carbon nanotube purity  

NASA Astrophysics Data System (ADS)

Transition-metal catalysts, fullerenes, graphitic carbon, amorphous carbon, and graphite flakes are the main impurities in carbon nanotubes. In this study, we demonstrate an easy and optimum method of cleaning SWCNTs and evaluating their purity. The purification method, which employed oxidative heat treatment followed by 6M HNO3, H2SO4, HNO3:H2SO4 and HCl acid reflux for 6h at 120°C and microwave digestion with 1.5M HNO3 for 0.5h at 210°C which was straightforward, inexpensive, and fairly effective. The purified materials were characterized by thermogravimetric analysis and nuclear techniques such as INAA, XRF and XRD.

Yuca, Neslihan; Camtakan, Zeyneb; Karatepe, Nilgün

2013-09-01

219

Industrially synthesized single-walled carbon nanotubes: compositional data for users, environmental risk assessments, and source apportionment  

Microsoft Academic Search

Commercially available single-walled carbon nanotubes (SWCNTs) contain large percentages of metal and carbonaceous impurities. These fractions influence the SWCNT physical properties and performance, yet their chemical compositions are not well defined. This lack of information also precludes accurate environmental risk assessments for specific SWCNT stocks, which emerging local legislation requires of nanomaterial manufacturers. To address these needs, we measured the

D. L. Plata; P. M. Gschwend; C. M. Reddy

2008-01-01

220

Optical and vibrational properties of single-wall carbon nanotubes  

NASA Astrophysics Data System (ADS)

This work is a study of the optical properties of single-wall carbon nanotubes (SWNTs) using continuous wave (CW) modulation spectroscopy and resonant Raman scattering. SWNTs comprise a nanoscale, quasi-1D system in which the electrons are strongly interacting, resulting in the photo-generation of excitons. Our optical studies have revealed the behavior of these excitons under a number of different perturbations to the system. We have used absorption, reflectance, electro-absorption (EA), photo-induced absorption (PA), charge-induced absorption (CIA), and resonant Raman scattering (RRS) on films of SWNTs. Our EA results provide strong evidence for the dominance of excitons in the optical absorption spectra of SWNT films. The absence of Franz-Keldysh oscillations and the presence of a derivative-like structure of the EA spectra indicate that the oscillator strength goes to the generation of excitons and not to interband electronic transitions. Furthermore, some of the photo-generated excitons are long-lived due to charge trapping in individual tubes within bundles, and this leads to a PA spectrum that is extraordinarily similar to the EA signal. When SWNTs are electrochemically doped we see that the exciton absorption is bleached due to k-space filling and screening of the excitons by the modified local dielectric, while there is very little shift in the exciton transition energies due to band-gap renormalization. Simultaneously the infrared absorption, which is due to Drude free-carriers absorption, is enhanced. A similar behavior is observed in the case of direct charge injection. The RRS of doped SWNT samples shows a frequency shift of many of the Raman-active modes that is commensurate with the macroscopic actuation observed in nanotube-based electrochemical devices. This indicates that doping-induced changes in the lattice are connected with softening and stiffening of the vibrational modes. Our results impact many proposed technologies that exploit the unique properties of SWNTs. Displays, batteries, and even photovoltaics that incorporate nanotubes are already in development. The performance and robustness of these devices could be improved when our results are taken into account.

Kennedy, W. Joshua

221

Diffusion of single-walled carbon nanotube under physiological conditions.  

PubMed

Single-walled carbon nanotube (SWNT) can be functionalized to target cells for drug delivery or cancer cells for their detection and therapy. Understanding their transport phenomena in vivo is a necessary step to unlock their medical potential. This work estimates the diffusion characteristics of SWNTs and their DNA-conjugated bio-hybrids under simulated or postulated physiological conditions using EPI-fluorescence microscopy (EFM). SWNT was shortened and dispersed in aqueous solution with the average length and diameter of 253 nm (+/-30.6 nm) and 1.6 nm (+/-0.34 nm), respectively, and tagged with a fluorophore, 1-pyrenebutanoic succinimidyl ester (PSE), through non-covalent pi stacking. DNA was attached to the PSE-SWNTs through carboxiimide based coupling procedure. Using the EFM, real-time videos were recorded under four different viscosities corresponding to four kinds of human body fluids: lymph (1.4 cP), bile (2.4 cP), blood (3-6 cP), and cytoplasm (10-30 cP), and processed to calculate diffusion coefficients based on random walk and speed. At 37 degreeC, diffusion coefficients of the SWNTs were estimated to be: 1.45 (+/-0.652) x 10(4) nm2/s (lymph), 0.91 (+/-0.205) x 10(4) nm2/s (bile), 0.59 (+/-0.179)x 10(4) nm2/s (blood), and 0.26 (+/-0.114)x 10(4) nm2/s (cytoplasm). Estimated diffusion coefficients of SWNT-DNA bio-hybrids were: 1.45 (+/-0.402) x 10(4) nm2/s (plasma), 0.62 (+/-0.212) x 10(4) nm2/s (bile), 0.41 (+/-0.142) x 10(4) nm2/s (blood), 0.38 (+/-0.257) x 10(4) nm2/s (cytoplasm). These outcomes should serve as key data for developing mathematical models of SWNT-based drug delivery, cell targeting, and its biodistribution. PMID:23858971

Judkins, John; Lee, Hyun Ho; Tung, Steve; Kim, Jin-Woo

2013-06-01

222

Adsorption of Bacillus subtilis on single-walled carbon nanotube aggregates, activated carbon and NanoCeram™  

Microsoft Academic Search

Adsorption equilibrium and kinetics of Bacillus subtilis spores on single-walled carbon nanotube aggregates were investigated to explore the possibility of using single-walled carbon nanotubes for concentration, detection and removal of pathogens from contaminated water sources. Batch adsorption experiments were conducted to determine adsorption kinetics and adsorption equilibrium of B. subtilis spores on single-walled carbon nanotube aggregates, activated carbon and NanoCeram™.

Venkata K. K. Upadhyayula; Shuguang Deng; Geoffrey B. Smith; Martha C. Mitchell

2009-01-01

223

A Novel Synthesis Route for Bimetallic CoCr–MCM-41 Catalysts with Higher Metal Loadings. Their Application in the High Yield, Selective Synthesis of Single-Wall Carbon Nanotubes  

SciTech Connect

We present a study on CoCr-MCM-41 catalysts with stable nm-sized particles. The focus is their promoting effect on the synthesis of Single-Wall Carbon Nanotubes (SWNT). Bimetallic CoCr-MCM-41 catalysts were synthesized by combined grafting and incorporation of metals in the framework. This synthesis allowed an increase in the maximum metal loading in the MCM-41 framework while maintaining nm-sized Co particles stable in high-temperature reactive environments. The SWNT yield was increased by more than 100% from the Co-MCM-41 catalyst. Cobalt is responsible for SWNT nucleation. The role of chromium is to anchor small cobalt particles during reduction and prevent their sintering into large unreactive particles. A larger fraction of the cobalt in the bimetallic catalysts becomes available for the SWNT synthesis when compared to the monometallic one, leading to a significant yield increase. Another effect of the addition of Cr was a shift of the SWNT diameter distribution to smaller nanotubes.

Zoican Loebick, C.; Lee, S; Derrouiche, S; Schwab, M; Chen, Y; Haller, G; Pfefferle, L

2010-01-01

224

Odako growth of dense arrays of single-walled carbon nanotubes attached to carbon surfaces  

Microsoft Academic Search

A novel process is demonstrated whereby dense arrays of single-walled carbon nanotubes (SWNT) are grown directly at the interface\\u000a of a carbon material or carbon fiber. This growth process combines the concepts of SWNT tip growth and alumina-supported SWNT\\u000a base growth to yield what we refer to as “odako” growth. In odako growth, an alumina flake detaches from the carbon

Cary L. Pint; Noe T. Alvarez; Robert H. Hauge

2009-01-01

225

An elastic shell model for characterizing single-walled carbon nanotubes.  

PubMed

This paper proposes a two-dimensional elastic shell model to characterize the deformation of single-walled carbon nanotubes using the in-plane rigidity, Poisson ratio, bending rigidity and off-plane torsion rigidity as independent elastic constants. It was found that the off-plane torsion rigidity of a single-walled carbon nanotube is not zero due to the off-plane change in the ?-orbital electron density on both sides of the nanotube. It was concluded that a three-dimensional elastic shell model of single-walled carbon nanotubes can be established with well-defined effective thickness. PMID:21825722

Wang, C Y; Zhang, L C

2008-04-08

226

A remote sensor for detecting methane based on palladium-decorated single walled carbon nanotubes.  

PubMed

The remote detection of the concentration of methane at room temperature is performed by a sensor that is configured by the combination of radio frequency identification (RFID), and functionalized carbon nanotubes (CNTs). The proposed sensor is schemed as a thin film RFID tag in a polyethylene substrate, on which a metal trace dipole, a metal trace T impedance matching networks, a 0.5 µm-CMOS RF/DC rectifier chipset and a sensor head of palladium-decorated single walled carbon nanotubes (Pd-SWCNTs) are surface mounted in cascade. The performances of the sensor are examined and described by the defined parameters of the received signal strength index (RSSI) and the comparative analog identifier (?AID). Results validate the sensor's ability to detect molecules of methane at room temperature, showing that the RSSI can increase 4 dB and the ?AID can increase 3% in response to methane concentrations ranging from zero to 100 ppm. PMID:23845931

Liu, Jian; Li, Guomin

2013-07-10

227

A Remote Sensor for Detecting Methane Based on Palladium-Decorated Single Walled Carbon Nanotubes  

PubMed Central

The remote detection of the concentration of methane at room temperature is performed by a sensor that is configured by the combination of radio frequency identification (RFID), and functionalized carbon nanotubes (CNTs). The proposed sensor is schemed as a thin film RFID tag in a polyethylene substrate, on which a metal trace dipole, a metal trace T impedance matching networks, a 0.5 ?m-CMOS RF/DC rectifier chipset and a sensor head of palladium-decorated single walled carbon nanotubes (Pd-SWCNTs) are surface mounted in cascade. The performances of the sensor are examined and described by the defined parameters of the received signal strength index (RSSI) and the comparative analog identifier (?AID). Results validate the sensor's ability to detect molecules of methane at room temperature, showing that the RSSI can increase 4 dB and the ?AID can increase 3% in response to methane concentrations ranging from zero to 100 ppm.

Liu, Jian; Li, Guomin

2013-01-01

228

40 CFR 721.10277 - Single-walled and multi-walled carbon nanotubes (generic) (P-10-40).  

Code of Federal Regulations, 2013 CFR

...false Single-walled and multi-walled carbon nanotubes (generic) (P-10-40...10277 Single-walled and multi-walled carbon nanotubes (generic) (P-10-40...generically as single-walled and multi-walled carbon nanotubes (PMN P-10-40)...

2013-07-01

229

The growth mechanism of single-walled carbon nanotubes with a controlled diameter  

NASA Astrophysics Data System (ADS)

Understanding the growth mechanism of carbon nanotube is important to control the structure and properties of carbon nanotubes. We examined several aspects of the single wall carbon nanotubes (SWCNTs) prepared by chemical vapor deposition (CVD) processes using ethanol with the additions of ferrocene and thiophene, focusing on the potential mechanisms leading to the differences in the diameters, structures, and conductivities of the SWCNTs formed. The diameter of SWCNTs could be controlled from ?1.0 to ?5.8 nm by adjusting the concentration of thiophene used. The larger diameter SWCNTs has a higher thermal stability than smaller-diameter SWCNTs. With increasing diameter, the electrical properties of the SWCNT change from mainly semi-conducting to metallic-like. The growth mechanism of SWCNTs was subsequently studied to understand the mechanism of thiophene controlled SWCNTs formation. This study could lead to improved control over the diameter and electronic properties of SWCNTs.

Yu, Fei; Yang, Mingxuan; Li, Fanglin; Su, Chang; Ma, Buyong; Yuan, Zhiwen; Chen, Junhong; Ma, Jie

2012-07-01

230

Identification of nitrogen dopants in single-walled carbon nanotubes by scanning tunneling microscopy.  

PubMed

Using scanning tunnelling microscopy and spectroscopy, we investigated the atomic and electronic structure of nitrogen-doped single walled carbon nanotubes synthesized by chemical vapor deposition. The insertion of nitrogen in the carbon lattice induces several types of point defects involving different atomic configurations. Spectroscopic measurements on semiconducting nanotubes reveal that these local structures can induce either extended shallow levels or more localized deep levels. In a metallic tube, a single doping site associated with a donor state was observed in the gap at an energy close to that of the first van Hove singularity. Density functional theory calculations reveal that this feature corresponds to a substitutional nitrogen atom in the carbon network. PMID:23829349

Tison, Yann; Lin, Hong; Lagoute, Jérôme; Repain, Vincent; Chacon, Cyril; Girard, Yann; Rousset, Sylvie; Henrard, Luc; Zheng, Bing; Susi, Toma; Kauppinen, Esko I; Ducastelle, François; Loiseau, Annick

2013-07-12

231

Cu/single-walled carbon nanotube laminate composites fabricated by cold rolling and annealing  

NASA Astrophysics Data System (ADS)

The remarkable mechanical, electrical and thermal properties of single-walled carbon nanotubes (SWCNTs) have attracted extensive research interest as structural and functional materials. In particular, SWCNTs have been used to reinforce polymers and ceramic composites and great progress has been made. For metal matrix composites, the limitation of the conventional manufacturing process and the difficulty in dispersing nanotubes within metal matrices hinder the development of metal matrix composites. In this paper, we demonstrate a successful fabrication of Cu/SWCNT laminate composites by combined techniques of cold rolling and annealing, using 19 layers of large-area SWCNT films sandwiched between 20 layers of Cu thin foils. The tensile strength and Young's modulus of the resultant laminate composites are 361 MPa and 132 GPa, respectively, exhibiting an improvement over the comparative pure Cu foils processed under identical conditions. These results suggest that good interfacial adhesions between nanotubes and the Cu matrix have been achieved after the rolling-annealing-rolling processes.

Li, Yan-Hui; Housten, William; Zhao, Yimin; Qiu Zhu, Yan

2007-05-01

232

Dynamics of Er-doped ultrashort pulse fiber laser using single wall carbon nanotube polyimide film  

Microsoft Academic Search

Dynamics of Er-doped ultrashort pulse fiber laser with single wall carbon nanotube polyimide film were investigated both experimentally and numerically. Dependence on output coupling ratio, temporal response of nanotube, and dispersion properties were discussed.

Norihiko Nishizawa; Yuto Nozaki; Yoichi Sakakibara; Emiko Itoga; Hiromichi Kataura

2011-01-01

233

New Method Developed To Purify Single Wall Carbon Nanotubes for Aerospace Applications.  

National Technical Information Service (NTIS)

Single wall carbon nanotubes have attracted considerable attention because of their remarkable mechanical properties and electrical and thermal conductivities. Use of these materials as primary or secondary reinforcements in polymers or ceramics could lea...

M. Lebron M. A. Meador

2003-01-01

234

Evidence for substitutional boron in doped single-walled carbon nanotubes  

SciTech Connect

Precise determination of acceptors in the laser ablation grown B doped single-walled carbon nanotubes (SWCNTs) has been elusive. Photoemission spectroscopy finds evidence for subpercent substitutional B in this material, which leads to superconductivity in thin film SWNT samples.

Ayala, P.; Pichler, T. [Faculty of Physics, University of Vienna, 1090 Wien (Austria); Reppert, J.; Rao, A. M. [Department of Physics and Astronomy and COMSET, Clemson University (United States); Grobosch, M.; Knupfer, M. [IFW Dresden, P.O. Box 270116, D-01171 Dresden (Germany)

2010-05-03

235

Optical Band Gap Modification of Single-Walled Carbon Nanotubes by Encapsulated Fullerenes  

Microsoft Academic Search

We report optical band gap modifications of single-walled carbon nanotubes upon C60 insertions by using photoluminescence and the corresponding excitation spectroscopy. The shifts in optical transition energies strongly depend on the tube diameter (dt) and the \\

Toshiya Okazaki; Shingo Okubo; Takeshi Nakanishi; Soon-Kil Joung; Takeshi Saito; Minoru Otani; Susumu Okada; Shunji Bandow; Sumio Iijima

2008-01-01

236

Theoretical and experimental studies of Schottky diodes that use aligned arrays of single-walled carbon nanotubes  

Microsoft Academic Search

We present theoretical and experimental studies of Schottky diodes that use aligned arrays of single-walled carbon nanotubes.\\u000a A simple physical model, taking into account the basic physics of current rectification, can adequately describe the single-tube\\u000a and array devices. We show that for as-grown array diodes, the rectification ratio, defined by the maximum-to-minimum-current-ratio,\\u000a is low due to the presence of metallic-single-walled

Xinning Ho; Lina Ye; Slava V. Rotkin; Xu Xie; Frank Du; Simon Dunham; Jana Zaumseil; John A. Rogers

2010-01-01

237

Preparation and characterization of sulfonic acid-functionalized single-walled carbon nanotubes  

Microsoft Academic Search

A strategy for the functionalization of single-walled carbon nanotubes is reported. The synthesis involved the conversion of fluorinated single-walled carbon nanotubes to the thiolated derivative assisted by phosphorous pentasulfide. The thiol group is then quantitatively oxidized to the sulfonic acid group. The extent of oxidation of the thiol precursor is confirmed using X-ray photoelectron spectroscopy, which proved to be immensely

Luqman Adams; Aderemi Oki; Tony Grady; Hylton McWhinney; Zhiping Luo

2009-01-01

238

Thermal decomposition and electron microscopy studies of single-walled carbon nanotubes  

Microsoft Academic Search

Thermoanalytical and electron microscopic methods were used as characterisation tools for the determination of the composition\\u000a of single walled carbon nanotube samples. Acid purification method of single-walled carbon nanotubes (SWCN) proved to be effective,\\u000a resulting in a three fold increase in the percentage of SWNTs present in the purified product as determined by thermogravimetric\\u000a analysis. In this work we report

A. W. Musumeci; G. G. Silva; W. N. Martens; E. R. Waclawik; R. L. Frost

2007-01-01

239

Exact study of lattice dynamics of single-walled carbon nanotubes  

Microsoft Academic Search

Based on the model of lattice dynamics with force-constant matrix, we have calculated phonon spectrum and then specific heats of single-walled carbon nanotubes. The results show that with a more complicated phonon spectrum, a single-walled carbon nanotube has analogous good thermal conductivity to the two-dimensional graphite. However, the ratio of thermal conductivity to phonon relaxation time is inversely proportional to

J. X. Cao; X. H. Yan; Y. Xiao; Y. Tang; J. W. Ding

2003-01-01

240

Affinity Studies on the Binding between DNA and Single-Walled Carbon Nanotubes  

Microsoft Academic Search

We report on our experimental studies on the binding between DNA and single-walled carbon nanotubes using combined techniques of UV-Vis, Raman spectroscopy and single-molecule fluorescence microscopy. The melting and re-annealing of double-stranded DNA (Poly A-U and calf thymus DNA) in the presence of single-walled carbon nanotubes showed temperature dependences distinctive from those of pure DNA, as measured with the spectrophotometer.

Qi Lu; Allen Parker; A. M. Rao; Pu-Chun Ke; Lyndon L. Larcom

2004-01-01

241

Single-wall carbon nanotube-based voltammetric sensor and biosensor  

Microsoft Academic Search

The pH-sensitive property of the single-wall carbon nanotube modified electrode based on the electroactive group on the single-wall carbon nanotube was explored by differential pulse voltammetry technique. In pH range 1–13 investigated in Britton–Robinson (B–R) buffer, the anodic peak shifted negatively along with the increase of pH exhibiting a reversible Nernstian response. Experiments were carried out to investigate the response

Zhiai Xu; Xu Chen; Xiaohu Qu; Jianbo Jia; Shaojun Dong

2004-01-01

242

Formation of single-walled bimetallic coinage alloy nanotubes in confined carbon nanotubes: molecular dynamics simulations.  

PubMed

The growth of single-walled bimetallic Au-Ag, Au-Cu and Ag-Cu alloy nanotubes (NTs) and nanowires (NWs) in confined carbon nanotubes (CNTs) has been investigated by using the classical molecular dynamics (MD) method. It is found that three kinds of single-walled gold-silver, gold-copper and silver-copper alloy NTs could indeed be formed in confined CNTs at any alloy concentration, whose geometric structures are less sensitive to the alloy concentration. And an extra nearly pure Au (Cu) chain will exist at the center of Au-Ag (Au-Cu and Ag-Cu) NTs when the diameters of the outside CNTs are big enough, thus producing a new type of tube-like alloy NWs. The bonding energy differences between the mono- and hetero-elements of the coinage metal atoms and the quasi-one-dimensional confinement from the CNT play important roles in suppressing effectively the "self-purification" effects, leading to formation of these coinage alloy NTs. In addition, the fluid-solid phase transition temperatures of the bimetallic alloy NTs are found to locate between those of the corresponding pure metal tubes. Finally, the dependences of the radial breathing mode (RBM) frequencies and the tube diameters of the alloy NTs on the alloying concentration were obtained, which will be very helpful for identifying both the alloying concentration and the alloy tube diameters in future experiments. PMID:24013729

Han, Yang; Zhou, Jian; Dong, Jinming; Yoshiyuki, Kawazoe

2013-09-25

243

Electronic transport characterization of Sc@C82 single-wall carbon nanotube peapods  

NASA Astrophysics Data System (ADS)

We present electrical transport and Raman measurements on individual single-wall carbon nanotubes filled with the paramagnetic metallofullerene Sc@C82. We find nearly all devices to be metallic p-type conductors, which we tentatively attribute to bandstructure modification of the nanotubes by the encapsulated Sc@C82 molecules. At low temperatures the peapod devices behave as quantum dots and transport is shown to be quantum coherent over distances of at least ~100 nm. Kondo features are observed at the lowest measurement temperatures of 50 mK. Our results are of fundamental interest because of the long spin coherence times of the unpaired electrons on the Sc@C82 molecules and the possibility this offers for studying one-dimensional spin chains in carbon nanotubes.

Cantone, A. L.; Buitelaar, M. R.; Smith, C. G.; Anderson, D.; Jones, G. A. C.; Chorley, S. J.; Casiraghi, C.; Lombardo, A.; Ferrari, A. C.; Shinohara, H.; Ardavan, A.; Warner, J.; Watt, A. A. R.; Porfyrakis, K.; Briggs, G. A. D.

2008-10-01

244

Fluorescent single-walled carbon nanotubes following the 1,3-dipolar cycloaddition of pyridinium ylides.  

PubMed

Pyridinium ylides generated from simple Krohnke salts undergo a 1,3-dipolar cycloaddition to single-walled carbon nanotubes (SWNTs) offering a simple and convenient method for the covalent modification of carbon nanotubes. The indolizine functionalized SWNTs generated, emit blue light when excited at 335 nm. The location and distribution of the functional groups was determined by AFM using electrostatic interactions with gold nanoparticles. While resonance Raman spectroscopy showed that the 1,3-dipolar cylcloaddition of the pyridinium ylides to the nanotube surface was selective for metallic and large diameter semiconducting SWNTs. The indolizine functionalized SWNTs were further characterized using FTIR, UV-vis-NIR, TGA-MS, and XPS. PMID:19569688

Bayazit, Mustafa K; Coleman, Karl S

2009-08-01

245

Opening and reversible filling of single-walled carbon nanotubes with various materials.  

PubMed

Single-walled carbon nanotubes have been advocated as perfect candidates for the sustainable miniaturisation of electronic and mechanical nanoscale devices. The encapsulation of selected compounds within the inner hollow cavity of SWNTs allows controlled preparation of nano-meter size "nanowires" and "nanocables" with purpose-tailored physical properties. Therefore is crucial to have control of opening and closing their tips. In a previous study we showed that molten metal hydroxide [MOH (M==Cs, Na)] is filled into the carbon nanotubes and can be easily washed out with water leaving opened nanotubes. Following this approach we have explored the use of milder ways to open SWNTs that can be easily scalable for the production of large amount of opened SWNTs. The opened tubes have then successfully been filled in solution with various inorganic and organic materials. PMID:17252765

Huh, Yoon; Shao, Lidong; Tobias, Gerard; Green, Malcolm L H

2006-11-01

246

Synthesis and characterization of platinum nanoparticles on single-walled Carbon nanotube "nanopaper" support  

NASA Astrophysics Data System (ADS)

We prepared several samples of carbon-nanotube-supported Pt nanoparticles that are potentially promising electrocatalysts for hydrogen fuel cells. Commercially obtained single-walled carbon nanotubes (SWNTs) were characterized by Raman Spectroscopy, SEM, TEM, EDS, and XANES. This multi-technique characterization allowed us to quantify the size and composition of metal impurities (Mo, Co) in SWNTs, to choose the best method to remove them, and characterize the effectiveness of their removal. After synthesizing a "nanopaper" (10-20 micrometer thick, free standing sheets of self-assembled SWNTs) we decorated it with Pt nanoparticles by electroless deposition. Formation of Pt nanoparticles was verified by EXAFS, and quantitative information about their size and structure was obtained.

Bromberg, Malka R.; Patlolla, Anitha; Segal, Rebecca; Feldman, Yishai; Wang, Qi; Iqbal, Zafar; Frenkel, Anatoly I.

2009-11-01

247

Near-infrared photoresponse in single walled carbon nanotube/polymer composite films  

NASA Astrophysics Data System (ADS)

We present a near-infrared photoresponse study of single-walled carbon nanotube/poly(3-hexylthiophene)-block-polystyrene polymer (SWCNT/P3HT-b-PS) composite films for different loading ratios of SWCNT in the polymer matrix. Compared to the pure SWCNT film, the photoresponse [(light current -- dark current)/dark current] is much larger in the SWCNT/polymer composite films. The photoresponse is up to 157% when SWCNTs are embedded in P3HT-b-PS while for a pure SWCNT film it is only 40%. We also show that the photocurrent strongly depends on the position of the laser spot with maximum photocurrent occurring at the metal--film interface. We explain the photoresponse due to exciton dissociations and charge carrier separation caused by a Schottky barrier at the metallic electrode - SWCNT interface

Sarker, Biddut K.; Arif, M.; Khondaker, Saiful I.

2010-03-01

248

Temperature dependent resistance of as-grown and chemical treated single walled carbon nanotubes films.  

PubMed

Single Walled Carbon Nanotube (SWCNT) films were directly synthesized via Floating Catalyst Chemical Vapor Deposition (FCCVD) method. Temperature dependent resistance measurements were carried out on the as-grown and chemical treated SWCNTs films. A "U" shaped curve was obtained for each sample, with a significant variation in the crossover temperatures between the as-grown and treated samples. A heterogeneous model was adopted to interpret the experimental data, revealing the coexistence of anisotropic 1D metallic conduction, conventional metallic conduction and fluctuation assisted tunneling. Our results implied very low barriers, verifying the good intertube and interbundle contacts in the directly synthesized SWCNTs films. We speculated that oxidization and acid treatments would affect the overall configuration of the films, leading to the changes in the temperature dependence of resistance. In addition, Raman and absorption spectra indicated that oxidization and acid process would cause moderate changes in the hole carrier concentration of the films. PMID:23646629

Cai, Le; Li, Jinzhu; Dong, Haibo; Zhao, Duan; Zhang, Xiaoxian; Zeng, Qingsheng; Zhou, Weiya; Xie, Sishen

2013-02-01

249

Low temperature conductive tip scanning of single walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

The low temperature conductance measurements of Carbon Nanotubes (CNT), and other nanostructures, are commonly conducted on samples with fixed leads, which provide the global information about the nanostructure's electronic properties. To measure local electronic properties, we have built a conductive tip Atomic Force Microscope (AFM). This AFM allows us to place a mobile contact anywhere along the tube and carry out local transport investigation, including measurements taken while we radially deform the nanotube with the tip. Our low temperature conductive tip AFM is suitable for operation in a helium refrigerator with a bore 1.25" or more, at temperatures of 4K or less. It uses a thermally compensated, nonmagnetic design based on the "Besocke Beetle". All movements are achieved by piezotubes, so heat load at low temperatures is small. For tip-surface distance control, we use a homemade frequency detection system based on a commercially available quartz tuning fork. The scanning tip is mounted on the tuning fork. We use a platinum/iridium tip rather than the more commonly used tungsten, as it does not form a native oxide. The tip is independently wired which allows us to measure the current flow along the tube. Previous low temperature AFMs used the conductive tip only to gate the nanotube. Our samples are CVD grown carbon nanotubes upon a silicon dioxide substrate, contacted by a palladium/gold grid. With our AFM, we have carried out the first low temperature scanning of conductance along nanotubes on insulating substrates. While radially deforming a metallic carbon nanotube with our tip, we have observed a reversible gap opening, indicating a metallic to semi-conducting transition. This result qualitatively matches theoretical predictions. We have observed Coulomb blockade in transport between carbon nanotubes and the tip by AFM for the first time. By gently perturbing the nanotube with the tip, we have increased the strength of some single electron conductance peaks while diminishing others. This result is probably due the perturbation of the probability density functions inside the nanotube. This novel instrument will allow us to study the local properties of a broad class of conductive nanostructures positioned on insulating substrates.

Prior, Matthew

250

New oscillation in terahertz magneto-optical effect of single-walled carbon nanotubes film  

Microsoft Academic Search

The magneto-optical Kerr effect of single-walled carbon nanotubes (SWNTs) film in the Terahertz region is theoretically studied by means of the Drude model. The calculation shows a new oscillation occurring near the plasma frequency as the origin of the magneto-optical Kerr effect for the single-walled nanotubes film. We propose that the amplitude of this near plasma frequency oscillation is directly

Jia-Guang Han; Zhi-Yuan Zhu; Yi Liao; Zhen-Xia Wang; Wei Zhang; Li-Tao Sun; Ting-Tai Wang

2004-01-01

251

Identifying individual single-walled and double-walled carbon nanotubes by atomic force microscopy.  

PubMed

We show that the number of concentric graphene cylinders forming a carbon nanotube can be found by squeezing the tube between an atomic force microscope tip and a silicon substrate. The compressed height of a single-walled nanotube (double-walled nanotube) is approximately two (four) times the interlayer spacing of graphite. Measured compression forces are consistent with the predicted bending modulus of graphene and provide a mechanical signature for identifying individual single-walled and double-walled nanotubes. PMID:18811211

DeBorde, Tristan; Joiner, J Caleb; Leyden, Matthew R; Minot, Ethan D

2008-09-24

252

Elastic strain of freely suspended single-wall carbon nanotube ropes  

NASA Astrophysics Data System (ADS)

We have induced large elastic strains in ropes of single-wall carbon nanotubes, using an atomic force microscope in lateral force mode. Freely suspended ropes were observed to deform as elastic strings with tension proportional to elongation. Ropes were elastically deformed over >10 cycles without showing signs of plastic deformation. The maximum strain observed, 5.8+/-0.9%, gives a lower bound of 45+/-7 GPa for the tensile strength (specifically, yield stress) of single-wall nanotube ropes.

Walters, D. A.; Ericson, L. M.; Casavant, M. J.; Liu, J.; Colbert, D. T.; Smith, K. A.; Smalley, R. E.

1999-06-01

253

Synthesis of single-walled carbon nanotubes by chemical vapor deposition and their electronic devices  

Microsoft Academic Search

This dissertation describes a series of studies on chemical vapor deposition (CVD) synthesis of single-walled carbon nanotubes (SWNTs) and their electronic applications. A novel finding on the relationship between the carbon feeding rate and the SWNT diameters and growth efficiency is summarized. Electronic devices, including polymer electrolyte gated carbon nanotube field effect transistors and Schottky barrier diodes, are fabricated and

Chenguang Lu

2006-01-01

254

Quantized molecular structural mechanics modeling for studying the specific heat of single-walled carbon nanotubes  

Microsoft Academic Search

We extend the molecular structural mechanics approach to the study of the specific heat of carbon nanotubes. The vibrational modes of the nanotube are quantized according to the theory of quantum mechanics. The partition function is directly expressed by the vibrational frequencies of carbon atoms. The specific heat of finite-length individual single-walled carbon nanotubes is calculated and the temperature dependence

Chunyu Li; Tsu-Wei Chou

2005-01-01

255

Conductivity enhancement in single-walled carbon nanotube bundles doped with K and Br  

NASA Astrophysics Data System (ADS)

Single-walled carbon nanotubes (SWNTs), prepared by metal-catalysed laser ablation of graphite, form close-packed bundles or `ropes. These rope crystallites exhibit metallic behaviour above 50K (ref. 2), and individual tubes behave as molecular wires, exhibiting quantum effects at low temperatures,. They offer an all-carbon host lattice that, by analogy with graphite and solid C60 (ref. 6), might form intercalation compounds with interesting electronic properties, such as enhanced electrical conductivity and superconductivity. Multi-walled nanotube materials have been doped with alkali metals and FeCl3 (ref. 8). Here we report the doping of bulk samples of SWNTs by vapour-phase reactions with bromine and potassium-a prototypical electron acceptor and donor respectively. Doping decreases the resistivity at 300K by up to a factor of 30, and enlarges the region where the temperature coefficient of resistance is positive (the signature of metallic behaviour). These results suggest that doped SWNTs represent a new family of synthetic metals.

Lee, R. S.; Kim, H. J.; Fischer, J. E.; Thess, A.; Smalley, R. E.

1997-07-01

256

Solubilizing polycarbonate-modified single-walled carbon nanotubes by simultaneously attaching octadecylamine  

Microsoft Academic Search

To dissolve polycarbonate-modified single-walled carbon nanotubes, octadecylamine was simultaneously attached to carbon nanotubes by ammonification. The functionalized carbon nanotubes are soluble in highly or normal polar organic solvents due to different polycarbonates: the poly (butylene-co-?-caprolactone carbonate) and octadecylamine-modified carbon nanotubes can dissolve in highly polar organic solvents such as dimethyl sulfoxide and dimethylformamide; the poly[(propylene oxide)-co-(carbon dioxide)-co-(maleic anhydride)] and octadecylamine-modified

Jin-Gang Yu; Ke-Long Huang; Qiaoqin Yang; Yan-Fei Liu

2009-01-01

257

All-printed and transparent single walled carbon nanotube thin film transistor devices  

NASA Astrophysics Data System (ADS)

We present fully transparent single-walled all-carbon nanotube thin film transistors (SWCNT TFT) fabricated using low-cost inkjet printing methods. Such a demonstration provides a platform towards low cost fully printed transparent electronics. The SWCNT TFTs were printed with metallic and semiconducting SWCNT using a room temperature printing process, without the requirement of expensive cleanroom facilities. The unoptimized SWCNT TFTs fabricated exhibited an Ion/off ratio of 92 and mobility of 2.27 cm2V-1s-1 and transmissivity of 82%. The combination of both high electrical performance and high transparency make all-SWCNT TFTs desirable for next generation transparent display backplanes and products such as Google Glass.

Sajed, Farzam; Rutherglen, Christopher

2013-09-01

258

Heteroepitaxial Growth of Single-Walled Carbon Nanotubes from Boron Nitride  

PubMed Central

The growth of single-walled carbon nanotubes (SWCNTs) with predefined structure is of great importance for both fundamental research and their practical applications. Traditionally, SWCNTs are grown from a metal catalyst with a vapor-liquid-solid mechanism, where the catalyst is in liquid state with fluctuating structures, and it is intrinsically unfavorable for the structure control of SWCNTs. Here we report the heteroepitaxial growth of SWCNTs from a platelet boron nitride nanofiber (BNNF), which is composed of stacked (002) planes and is stable at high temperatures. SWCNTs are found to grow epitaxially from the open (002) edges of the BNNFs, and the diameters of the SWCNTs are multiples of the BN (002) interplanar distance. In situ transmission electron microscopy observations coupled with first principles calculations reveal that the growth of SWCNTs from the BNNFs follows a vapor-solid-solid mechanism. Our work opens opportunities for the control over the structure of SWCNTs by hetero-crystallographic epitaxy.

Tang, Dai-Ming; Zhang, Li-Li; Liu, Chang; Yin, Li-Chang; Hou, Peng-Xiang; Jiang, Hua; Zhu, Zhen; Li, Feng; Liu, Bilu; Kauppinen, Esko I.; Cheng, Hui-Ming

2012-01-01

259

How catalysts affect the growth of single-walled carbon nanotubes on substrates.  

PubMed

Direct growth of single-walled carbon nanotubes (SWNTs) on flat substrates by chemical vapor deposition (CVD) is very important for the application of SWNTs in nanodevices. In the growth process, catalysts play an important role in controlling the structure of SWNTs. Over the years, we have systematically studied the size-controlled synthesis of Fe-based nanoparticles and the CVD growth of SWNTs, especially the horizontally aligned SWNTs, catalyzed by these produced nanoparticles. Some new catalysts were also developed. Among them, Cu is shown to be a superior catalyst for growing SWNT arrays on both silicon and quartz substrates and Pb is a unique catalyst from which one can obtain SWNTs without any metallic contaminant. SWNTs prepared with both Cu and Pb are very suitable for building high-performance nanodevices. These studies are also very helpful for further understanding the growth mechanism of SWNTs. PMID:20437500

Li, Yan; Cui, Rongli; Ding, Lei; Liu, Yu; Zhou, Weiwei; Zhang, Yan; Jin, Zhong; Peng, Fei; Liu, Jie

2010-04-01

260

Light-induced selective deposition of Au nanoparticles on single-wall carbon nanotubes.  

PubMed

Novel applications of single-walled carbon nanotubes (SWNT) rely on the development of new strategies to make them easier to handle without affecting their structural properties. In this work, we have selectively deposited Au nanoparticles (Au NP) on SWNT assisted by UV light irradiation. XPS analysis and UV-vis spectroscopy indicate that the deposition occurs at the defects generated after oxidation of the SWNT. By addition of n-dodecylthiol, the separation of oxidized tubes with Au NP (Au-ox-SWNT) from tubes devoid of Au NP (bare tubes, b-SWNT) was achieved. Raman and UV-vis-NIR spectra indicate that UV irradiation induces a faster nucleation of Au NP on metallic SWNT. This new technique can be useful for the preparation of nanohybrid composites with enhanced properties, as increased thermal stability, and to obtain purified SWNT. PMID:20866064

Quintana, Mildred; Ke, Xiaoxing; Van Tendeloo, Gustaaf; Meneghetti, Moreno; Bittencourt, Carla; Prato, Maurizio

2010-10-26

261

Ethanol sensor development using three-dimensional single-walled carbon nanotube networks  

NASA Astrophysics Data System (ADS)

A novel ethanol sensor using three-dimensional single-walled carbon nanotube networks (3D-SWNTs) with an alkaline electrolyte solution has been developed. A cyclic voltammetry was used to examine the electrochemical response of the sensor. The relationship between response currents and ethanol concentrations was found to be linear for the ethanol concentrations' range from 1 to 5%. The CV performance test showed the best sensitivity was 0.0024 mAmM -1cm-2 with the 3D-SWNT electrode having no Pt particle loading. The Pt-free electrode gave better performance than platinum-coated 3D-SWNTs electrodes did. Since the 3D-SWNTs electrode without using Pt metal loading detects ethanol concentrations (1--5%) with high sensitivity and accuracy, it can lower the fabrication cost for potential commercial application.

Chao, Wan-Jung

262

Scaling properties in transistors that use aligned arrays of single-walled carbon nanotubes.  

PubMed

Recent studies and device demonstrations indicate that horizontally aligned arrays of linearly configured single-walled carbon nanotubes (SWNTs) can serve as an effective thin film semiconductor material, suitable for scalable use in high-performance transistors. This paper presents the results of systematic investigations of the dependence of device properties on channel length, to reveal the role of channel and contact resistance in the operation. The results indicate that, for the range of channel lengths and SWNT diameters studied here, source and drain contacts of Pd yield transistors with effectively Ohmic contacts that exhibit negligible dependence of their resistances on gate voltage. For devices that use Au, modulation of the resistance of the contacts represents a significant contribution to the response. Extracted values of the mobilities of the semiconducting SWNTs and the contact resistances associated with metallic and semiconducting SWNTs are consistent with previous reports on single tube test structures. PMID:20050675

Ho, Xinning; Ye, Lina; Rotkin, Slava V; Cao, Qing; Unarunotai, Sakulsuk; Salamat, Shuaib; Alam, Muhammad A; Rogers, John A

2010-02-10

263

Energy loss of the electron system in individual single-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

We characterize the energy loss of the non-equilibrium electron system in individual metallic single-walled carbon nanotubes at low temperature. Using Johnson noise thermometry, we demonstrate that, for a nanotube with ohmic contacts, the dc resistance at finite bias current directly reflects the average electron temperature. This enables a straightforward determination of the thermal conductance associated with cooling of the nanotube electron system. In analyzing the temperature- and length-dependence of the thermal conductance, we consider contributions from acoustic phonon emission, optical phonon emission, and hot electron outdiffusion [1]. In the same sample, we also characterize the radio frequency heterodyne response. Distinct responses are seen from bolometric detection and from the electrical nonlinearity due to non-ohmic contacts. [4pt] [1] D.F. Santavicca, J.D. Chudow, D.E. Prober, M.S. Purewal, and P. Kim, Nano Lett. 10, 4538 (2010).

Santavicca, Daniel; Chudow, Joel; Prober, Daniel; Purewal, Meninder; Kim, Philip

2011-03-01

264

Parallel arrays of individually addressable single-walled carbon nanotube field-effect transistors  

NASA Astrophysics Data System (ADS)

High-throughput field-effect transistors (FETs) containing over 300 disentangled, high-purity chemical-vapor-deposition-grown single-walled carbon nanotube (SWNT) channels have been fabricated in a three-step process that creates more than 160 individually addressable devices on a single silicon chip. This scheme gives a 96% device yield with output currents averaging 5.4 mA and reaching up to 17 mA at a 300 mV bias. Entirely semiconducting FETs are easily realized by a high current selective destruction of metallic tubes. The excellent dispersity and nearly-defect-free quality of the SWNT channels make these devices also useful for nanoscale chemical and biological sensor applications.

Lastella, Sarah; Mallick, Govind; Woo, Raymond; Karna, Shashi P.; Rider, David A.; Manners, Ian; Jung, Yung Joon; Ryu, Chang Y.; Ajayan, Pulickel M.

2006-01-01

265

Single chirality extraction of single-wall carbon nanotubes for the encapsulation of organic molecules.  

PubMed

The hollow inner spaces of single-wall carbon nanotubes (SWCNTs) can confine various types of molecules. Many remarkable phenomena have been observed inside SWCNTs while encapsulating organic molecules (peapods). However, a mixed electronic structure state of the surrounding SWCNTs has impeded a detailed understanding of the physical/chemical properties of peapods and their device applications. We present a single-chirality purification method for SWCNTs that can encapsulate organic molecules. A single-chiral state of (11,10) SWCNTs with a diameter of 1.44 nm, which is large enough for molecular encapsulation, was obtained after a two-step purification method: metal-semiconductor sorting and cesium-chloride sorting. The encapsulation of C(60) to the (11,10) SWCNTs was also succeeded, promising a route toward single-chirality peapod devices. PMID:22647140

Kawai, Masatoshi; Kyakuno, Haruka; Suzuki, Takuya; Igarashi, Toru; Suzuki, Hironori; Okazaki, Toshiya; Kataura, Hiromichi; Maniwa, Yutaka; Yanagi, Kazuhiro

2012-06-04

266

Collective electronic excitations in magnetically aligned single wall carbon nanotubes studied by Raman spectroscopy  

NASA Astrophysics Data System (ADS)

Samples with magnetically aligned single wall carbon nanotubes (SWNT) have been studied by Raman spectroscopy in the low frequency spectral range: 10 - 700 cm-1. A novel Raman-active electronic collective excitation has been observed. At room temperature the excitation band is at about 30 cm-1. The band dramatically strengthens and softens down to about 15 cm-1 with sample cooling below 50 K. The polarization dependence of the Raman spectra was analyzed for laser excitation energies in resonance with electronic transitions and it was compared to that in the case of non-resonant excitation. Strong anisotropy of Raman response function of the SWNT has been observed: for polarization parallel to the direction of the nanotubes the electronic excitation band is about 4 times stronger than that for the perpendicular direction. The origin of the 1-D electronic excitation in metallic SWNT will be discussed.

Blumberg, G.; Gozar, A.; Dennis, B. S.; Sirenko, A. A.; Eklund, P. C.; Walters, D. A.; Casavant, M. J.; Schmidt, J.; Smalley, R. E.

2001-03-01

267

Covalently Bridging Gaps in Single-Walled Carbon Nanotubes with Conducting Molecules  

NASA Astrophysics Data System (ADS)

Molecular electronics is often limited by the poorly defined nature of the contact between the molecules and the metal surface. We describe a method to wire molecules into gaps in single-walled carbon nanotubes (SWNTs). Precise oxidative cutting of a SWNT produces carboxylic acid-terminated electrodes separated by gaps of <=10 nanometers. These point contacts react with molecules derivatized with amines to form molecular bridges held in place by amide linkages. These chemical contacts are robust and allow a wide variety of molecules to be tested electrically. In addition to testing molecular wires, we show how to install functionality in the molecular backbone that allows the conductance of the single-molecule bridges to switch with pH.

Guo, Xuefeng; Small, Joshua P.; Klare, Jennifer E.; Wang, Yiliang; Purewal, Meninder S.; Tam, Iris W.; Hong, Byung Hee; Caldwell, Robert; Huang, Limin; O'Brien, Stephen; Yan, Jiaming; Breslow, Ronald; Wind, Shalom J.; Hone, James; Kim, Philip; Nuckolls, Colin

2006-01-01

268

Second-order harmonic and combination modes in graphite, single-wall carbon nanotube bundles, and isolated single-wall carbon nanotubes  

Microsoft Academic Search

We report a study of second-order combination and overtone modes in highly ordered pyrolytic graphite (HOPG), in single-wall carbon nanotube (SWNT) bundles and in isolated SWNTs. We found both dispersive and nondispersive Raman bands in the range 1650-2100 cm-1, and we show that the appearance and frequency versus laser energy Elaser behavior of these features are in agreement with predictions

V. W. Brar; Ge. G. Samsonidze; M. S. Dresselhaus; G. Dresselhaus; R. Saito; A. K. Swan; M. S. Ünlü; B. B. Goldberg; A. G. Souza Filho; A. Jorio

2002-01-01

269

An efficient strategy for the purification of cloth-like single walled carbon nanotube soot produced by arc discharge  

Microsoft Academic Search

High purity single walled carbon nanotubes (SWCNTs) were prepared from arc discharge produced cloth-like soot by a new purification strategy, in which liquid oxidation and steam oxidation were combined with a freeze-drying process to remove the metallic and carbonaceous impurities. The process gives a product of >98% purity, which is acquired from a gram-scale dirty raw soot with an overall

Wei Guo; Zengpei Dou; He. Li; Zujin Shi; Hongfang Sun; Yuanfang Liu

2010-01-01

270

The structural and electronic properties of (10,0) zigzag Single-Wall Carbon Nanotubes modified by thiophene groups  

NASA Astrophysics Data System (ADS)

In this letter, modifications of (10,0) functionalized zigzag Single-Wall Carbon Nanotubes in different sites by thiophene groups were studied using density functional theory. Geometric structures and electronic properties were investigated. After modification a significant change was observed in band structure and density of states and metallic properties were obtained. The best result for application in organic photovoltaic cells was achieved when two organic groups were placed on opposite sides of the wall of the SWCNT symmetrically.

Hamadanian, Masood; Tavangar, Zahra; Naseh, Sara

2013-10-01

271

Large-scale synthesis of single-wall carbon nanotubes by catalytic chemical vapor deposition (CCVD) method  

Microsoft Academic Search

The large-scale production of single-wall carbon nanotubes (SWNTs) is reported. Large quantities of SWNTs can be synthesised by catalytic decomposition of methane over well-dispersed metal particles supported on MgO at 1000°C. The thus produced SWNTs can be separated easily from the support by a simple acidic treatment to obtain a product with high yields (70–80%) of SWNTs. Because the typical

J.-F Colomer; C Stephan; S Lefrant; G Van Tendeloo; I Willems; Z Kónya; A Fonseca; Ch Laurent; J. B Nagy

2000-01-01

272

A green access to highly pure single-walled carbon nanotubes by taurocholate-assistant dispersion and centrifugation  

NASA Astrophysics Data System (ADS)

Raw single-walled carbon nanotubes produced by arc discharge were oxidized in the air to eliminate amorphous carbon, and then dispersed in the aqueous solution of sodium taurocholate supersonically. Thus obtained stable dispersion was subjected to centrifugation, and the metal catalysts and varying carbon impurities were separated with carbon nanotubes. The efficiency of the above procedure was confirmed by scanning electron microscope observation, thermogravimetry, and optical absorption and Raman spectroscopic analyses. The advantage of this procedure lies in easiness, high purity, and no pollution to environment.

Lian, Yongfu

2009-09-01

273

Effect of static and dynamic charges on the electronic transport properties of single wall carbon nanotube transistors and interconnects  

NASA Astrophysics Data System (ADS)

In recent years, carbon nanotubes have emerged as a subject of considerable curiosity and attention, due to their unique properties. From an electronic materials perspective, carbon nanotubes have been repeatedly touted as the future of micro- and nano-electronics technology. Capable of being both metallic and semiconducting, single wall carbon nanotubes have generated visions of an all-nanotube architecture in the not too distant future. Single wall carbon nanotubes have also displayed exotic behavior at low temperatures, spurring a rush of new discoveries and advances down to the level of manipulating individual electrons in nanotubes, the ultimate miniaturization. As research makes significant advances towards these goals, a number of challenges have also appeared. Particularly, it has been realized that single wall carbon nanotubes are extremely sensitive to perturbations in their immediate environment, which might drastically alter their fundamental properties. While single wall nanotubes are physically robust, they appear to electronically very fragile. On the other hand, the effect of external perturbations has actually opened a new door to providing further insights into the fundamental electronic structure and properties of these nanotubes. The research leading to this thesis has focused on unraveling the origin and effect of some such perturbations on electronic and electrical transport properties of individual single wall carbon nanotubes. In order to reach this stage, a number of recent fundamental observations pertaining to nanotube field effect transistors, single electron transistors and ballistic conductors were first reproduced. Single wall carbon nanotubes were grown by thermal chemical vapor deposition techniques on silicon dioxide substrates under optimum conditions. The nanotubes were characterized by techniques like scanning probe microscopy and Raman spectroscopy. Test structures were fabricated by photolithography and electron beam lithography and metallization. Electrical measurements were conducted at temperatures ranging from room temperature to 25K. One of the most obvious environmental effects appeared in the form of hysteresis in the transfer characteristics of nanotube field effect transistors and single electron transistors. While this hysteresis has been reported previously, its origins have remained a subject of significant debate. A detailed study of the hysteresis phenomenon as a function of various parameters revealed convincing evidence to support the theory that the origin of this hysteresis is in fact different from similar hysteresis observed in silicon bases MOSFETs. Based on these findings, a model was developed allowing us to simulate the effect of various parameters on the hysteresis, and show excellent fitting of experimental data to the model.

Vijayaraghavan, Aravind

274

Single-wall carbon nanotubes with diameters approaching 6 nm obtained by laser vaporization  

Microsoft Academic Search

Single-wall carbon nanotubes (SWNTs) with large diameters from 2 to 5.6 nm were prepared by pulsed laser vaporization of carbon rods doped with Co, Ni and FeS in an atmosphere of Ar:H2. The SWNT material was characterized by SEM, HRTEM, Raman, IR, UV–VIS–NIR absorption spectroscopy and thermogravimetric analysis.

Sergei Lebedkin; Peter Schweiss; Burkhard Renker; Sharali Malik; Frank Hennrich; Marco Neumaier; Carsten Stoermer; Manfred M Kappes

2002-01-01

275

Specific heats of dilute neon inside a long single-walled carbon nanotube  

Microsoft Academic Search

An elegant formula for coordinates of carbon atoms in a unit cell of a single-walled nanotube (SWNT) is presented and the potential of neon (Ne) inside an infinitely long SWNT is analytically derived under the condition of the Lennard-Jones potential between Ne and carbon atoms. Specific heats of dilute Ne inside a long (20, 20) SWNT are calculated at different

Z. C. Tu; Z. C. Ou-Yang

2003-01-01

276

Isotope effect on phonon spectra in single-walled carbon nanotubes  

Microsoft Academic Search

Carbon nanotubes are usually made up of C12 atoms. By adopting the force constant model, the effects of isotope doping with C13 on the vibrational, optical, and thermal properties of single-walled carbon nanotubes are theoretically investigated, including the phonon eigenmodes and density of states, the Raman scattering spectra, and specific heat. Three types of doping patterns (axial stripes, circumferential bands

Yong-Qiang Cheng; Shu-Yun Zhou; Bang-Fen Zhu

2005-01-01

277

Theoretical calculations of thermophysical properties of single-wall carbon nanotube bundles  

Microsoft Academic Search

Carbon nanotube bundles are promising thermal interfacial materials due to their excellent thermal and mechanical characteristics. In this study, the phonon dispersion relations and density of states of the single-wall carbon nanotube bundles are calculated by using the force constant model. The calculation results show that the inter-tube interaction leads to a significant frequency raise of the low frequency modes.

Ting-Ting Miao; Meng-Xuan Song; Wei-Gang Ma; Xing Zhang

2011-01-01

278

Adsorption of polyaromatic hydrocarbons on single wall carbon nanotubes of different functionalities and diameters  

Microsoft Academic Search

Adsorption from toluene solution of phenanthrene and tetracene on single wall carbon nanotubes (SWCNT) is measured. Comparison of adsorbents such as laser ablation and HipCO samples reveals multiple factors influencing the adsorption mechanism. Acid functionalized carbon nanotubes have shown markedly increased adsorbability for the polyaromatic molecules. The linear tetracene molecule's adsorption is more promoted on nanotubes with increasing diameter, but

Suzana Gotovac; Cheol-Min Yang; Yoshiyuki Hattori; Kunimitsu Takahashi; Hirofumi Kanoh; Katsumi Kaneko

2007-01-01

279

Enhancing Mass Transport for Synthesizing Single-Walled Carbon Nanotubes via Micro Chemical Vapor Deposition  

Microsoft Academic Search

Miniaturization is introduced as a novel methodology to enhance mass transport in a chemical vapor deposition process. As a result, amorphous carbon formation during the synthesis of single-walled carbon nanotubes (SWNTs) can be deterred. Miniaturization also maintains a laminar flow pattern to ensure a stable growth condition. A system with micrometer-sized reaction chambers has been constructed to experimen- tally verify

Qin Zhou; Liwei Lin

2011-01-01

280

Quantum Mechanical Characterization of Single Walled Carbon Nanotube (SWCNT) to Evaluate Stability and Conductivity  

Microsoft Academic Search

Single Walled Carbon Nanotube (SWCNT) is known to have unique thermodynamic and electrical properties which mainly depends upon the chiral index values (n, m). Quantum mechanical modeling and simulation studies were conducted for these samples to characterize the above properties. The energy gap of conducting carbon nano tubes has been found to be negligibly small. Armchair configuration with (n=m) is

Anirudh Ranganath; G. Ashish; K. Varun Gopal; K. N. Kutty; P. K. Krishnan Namboori; D. Gopakumar

2010-01-01

281

Determination of redox states of (n,m)single-walled carbon nanotubes  

Microsoft Academic Search

Since the discovery of carbon nanotubes (CNTs), many groups have endeavored to understand the fundamental properties of the CNTs and explored their applications in nanomaterials science and engineering. The electronic structures of CNTs, one of the fundamental features of nanotubes, strongly depend on their chiralities. We discovered a method to determine the precise redox states of isolated single-walled carbon nanotube

Naotoshi Nakashima

2011-01-01

282

Radical functionalization of single-walled carbon nanotubes with azo(bisisobutyronitrile)  

NASA Astrophysics Data System (ADS)

The isobutyronitryl groups from thermal decomposition of azobisisobutyronitrile in a 1,2-dichlorobenzene solution were successfully attached to the sidewalls of single-walled carbon nanotubes; thermogravimetic analysis shows a weight loss of 20% (compared to raw SWNTs), which was calculated to be ca. 1 isobutyronitryl group in 23 carbon atoms.

Wang, Xianbao; Li, Shaoqing; Xu, Yang; Wan, Li; You, Haijun; Li, Qin; Wang, Shimin

2007-07-01

283

Fluorescence quenching of dyes covalently attached to single-walled carbon nanotubes.  

PubMed

The development of chromophore-carbon nanotube hybrids requires efficient and accurate methods to investigate their photophysical properties. Using the ability of the fluorescence labeling of surface species (FLOSS) technique to determine the density of covalently attached dyes to the surface of single-walled carbon nanotubes (SWCNTs), the luminescence of dye-SWCNT hybrids was quantitatively studied with two chromophores: dansyl hydrazine (DH) and panacyl bromide (PB). The fluorescence intensity of PB-SWCNT hybrids was reduced by 20-80% compared to that of free PB. A strong positive correlation between the degree of quenching and the residual metal impurity content in the SWCNT sample suggests that quenching of fluorescence of PB in PB-SWCNTs may be caused by the metal impurities and not by SWCNTs. On the contrary, the intensity of fluorescence of DH-SWCNT hybrids was reduced by almost 2 orders of magnitude compared to free DH, independent of the residual metal content in the SWCNT sample, suggesting that quenching of fluorescence in DH-SWCNT hybrids might occur via charge transfer from DH chromophores to SWCNTs, and revealing the potential of DH-SWCNT hybrids for solar light harvesting applications. PMID:21766814

Chiu, Cheuk Fai; Dementev, Nikolay; Borguet, Eric

2011-07-18

284

Single walled carbon nanotube growth and chirality dependence on catalyst composition  

NASA Astrophysics Data System (ADS)

Vertical arrays of single walled carbon nanotubes (VA-SWNTs) were grown using bi-metallic nanoparticle pro-catalysts. Iron oxide particles were doped with varying quantities of first row transition metals (Mn, Co, Ni, and Cu) for a comparative study of the growth of nanotubes. VA-CNT samples were verified using scanning electron microscopy, and characterized using resonance Raman spectroscopy. The length of the VA-CNTs is used as a measure of catalyst activity: the presence of dopants results in a change in the CNT length and length distribution. Cross correlation of the Raman spectra reveal variations in the distribution of radial breathing mode peaks according to the pro-catalyst composition. The formation of various chirality nanotubes is constant between repetitive runs with a particular catalyst, but may be controlled by the identity and concentration of the metal dopants within the iron catalyst. These results demonstrate that the composition of the catalyst is a major driving force toward type selective growth of nanotubes.Vertical arrays of single walled carbon nanotubes (VA-SWNTs) were grown using bi-metallic nanoparticle pro-catalysts. Iron oxide particles were doped with varying quantities of first row transition metals (Mn, Co, Ni, and Cu) for a comparative study of the growth of nanotubes. VA-CNT samples were verified using scanning electron microscopy, and characterized using resonance Raman spectroscopy. The length of the VA-CNTs is used as a measure of catalyst activity: the presence of dopants results in a change in the CNT length and length distribution. Cross correlation of the Raman spectra reveal variations in the distribution of radial breathing mode peaks according to the pro-catalyst composition. The formation of various chirality nanotubes is constant between repetitive runs with a particular catalyst, but may be controlled by the identity and concentration of the metal dopants within the iron catalyst. These results demonstrate that the composition of the catalyst is a major driving force toward type selective growth of nanotubes. Electronic supplementary information (ESI) available: Example of the protocol for fitting and normailizing the Raman data set. See DOI: 10.1039/c3nr03142j

Orbaek, Alvin W.; Owens, Andrew C.; Crouse, Christopher C.; Pint, Cary L.; Hauge, Robert H.; Barron, Andrew R.

2013-09-01

285

Photochemical modification of single-walled carbon nanotubes using HPHMP photoinitiator for enhanced organic solvent dispersion  

Microsoft Academic Search

Photochemical modification of single-walled carbon nanotubes (SWCNTs) was carried out by covalent attachment of 2-propanol-2-yl\\u000a radicals on the surface of SWCNTs, which were engendered by the photolysis of 1-[4-(2-Hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propane-1-one\\u000a (HPHMP) under ultraviolet (UV) light. Pristine single-walled carbon nanotubes (p-SWCNTs) were dispersed in acetone along with\\u000a HPHMP photoinitiator. After that, the mixture was irradiated by UV light to generate the free

Mirza Nadeem Ahmad; Maria Nadeem; Yuhong Ma; Wantai Yang

2010-01-01

286

Single-walled carbon nanotubes modified by ionic liquid as antiwear additives of thermoplastics  

Microsoft Academic Search

Pristine single-walled carbon nanotubes (CNTs) were dispersed in the room-temperature ionic liquid (IL) 1-octyl, 3-methylimidazolium tetrafluoroborate ([OMIM]BF4) by grinding and ultrasounds. Excess IL was removed to obtain single-walled carbon nanotubes modified by [OMIM]BF4 (mCNTs). mCNTs were added in a 1wt.% to polystyrene (PS), polymethylmethacrylate (PMMA) and polycarbonate (PC) to obtain PS+mCNT, PMMA+mCNT and PC+mCNT. The dry tribological performance of the

F. J. Carrión; C. Espejo; J. Sanes; M. D. Bermúdez

2010-01-01

287

Tunable assembly of carbon nanospheres on single-walled carbon nanotubes.  

PubMed

We have developed a process for spontaneous assembly of carbon nanospheres on aligned or nonaligned single-walled carbon nanotubes (SWNTs) by virtue of plasma-enhanced chemical vapor deposition (PECVD). The formation of carbon nanospheres with a uniform size of 30-60 nm is a catalyst-free process and strongly dependent on the applied plasma power and other factors. Both co-deposition and post-deposition approaches have been developed for effective assembly of carbon nanospheres on SWNTs. Furthermore, the method developed here also allows us to tailor the density and size of carbon nanospheres along nanotubes in a controllable way. The heterojunction structure based on different types of carbon demonstrated in this study represents a new hybrid manner for building complex systems which are promising for various applications. PMID:20603535

Qu, Liangti; Zhang, Han; Zhu, Jia; Dai, Liming

2010-07-06

288

Carbon Single-Wall Nanatube Growth in a Volumetrically Confined Arc Discharge System  

SciTech Connect

Carbon nanotubes hold significant promise for a vast number of materials applications due to their unique mechanical, electrical, and gas storage properties. Although carbon single-wall nanotubes (SWNTs) have been synthesized since 1993 by the arc discharge method, and numerous other synthesis methods have since been developed, no method has yet produced 100% pure carbon nanotubes. Instead, a significant amount of impurities—various carbon structures and metal catalysts—are present in the raw soot. While arc discharge was the first method for SWNT synthesis, it also produces more impure raw soot in comparison to the more recently developed laser vaporization, which has produced the purest raw soot to date but is much slower. Geometry and thermal gradient are appreciably different between traditional arc discharge systems and laser vaporization systems. We report that, by incorporating some characteristics inherent to a laser vaporization system into an arc discharge system, improvement in the yield of SWNT raw soot may be achieved. This is accomplished by confining the arc within a 50 mm diameter quartz tube, similar to laser vaporization. We find through transmission electron microscopy and Raman spectroscopy that SWNTs are made in significant numbers in this confined arc discharge system, comparable to laser vaporization synthesized material. Further study is, however, required to prove reproducibility and attain an exact value for the purity of the produced raw soot.

Franz, K.J.; Alleman, J.L.; Jones, K.M.; Dillon, A.C.; Heben, M.J.

2004-01-01

289

Theoretical study of armchair single-walled carbon nanotubes in the presence of a strong laser field: high harmonic generation  

NASA Astrophysics Data System (ADS)

The nonlinear optical response of armchair single-walled carbon nanotubes under high-intensity laser irradiation is investigated theoretically and numerically because the generation of high harmonics requires a strong laser field and come from the nonlinear motion of ? electrons in carbon nanotubes. A nonperturbative approach is performed to investigate the effect of group velocity on the high harmonics spectrum by nanotubes. A set of the quantum kinetic equations is derived, which includes coupled equations for the density matrix. By solving the density matrix and the current density equations numerically, we have studied the high-order harmonic generation from metallic carbon nanotubes driven by an electromagnetic external field.

Daneshfar, Nader; Bahari, Ali

2013-01-01

290

Toxicity assessment of single-walled carbon nanotubes  

Microsoft Academic Search

The objective of this study was to investigate the potential adverse health effects of occupational exposure to SWCNT dust using various in vitro approaches. Lung epithelium (represented by A549 and NHBE cells) was chosen as target cell model and exposed to minimally processed particle samples under submerse conditions and effects were compared to that of carbon black and crocidolite asbestos

Eva Herzog

2009-01-01

291

Gas-phase purification of single-wall carbon nanotubes  

Microsoft Academic Search

A gas-phase purification method for raw nanotube material has been developed which incorporates a chlorine, water, and hydrogen chloride gas mixture to remove unwanted carbon. The evolved gases can be easily monitored by infrared spectroscopy to follow the cleaning process. The quality of the final material was verified by SEM (scanning electron microscopy), TGA (thermogravimetric analysis), and UV-vis (ultraviolet and

John L. Zimmerman; Robert Kelley Bradley; Chad B. Huffman; Robert H. Hauge; John L. Margrave

2000-01-01

292

Storage of hydrogen in single-walled carbon nanotubes  

Microsoft Academic Search

Pores of molecular dimensions can adsorb large quantities of gases owing to the enhanced density of the adsorbed material inside the pores1, a consequence of the attractive potential of the pore walls. Pederson and Broughton have suggested2 that carbon nanotubes, which have diameters of typically a few nanometres, should be able to draw up liquids by capillarity, and this effect

A. C. Dillon; K. M. Jones; T. A. Bekkedahl; C. H. Kiang; D. S. Bethune; M. J. Heben

1997-01-01

293

Single walled carbon nanotube networks as substrates for bone cells  

Microsoft Academic Search

A central effort in biomedical research concerns the development of materials for sustaining and controlling cell growth. Carbon nanotube based substrates have been shown to support the growth of different kinds of cells. However the underlying molecular mechanisms remain poorly defined. To address the fundamental question of mechanisms by which nanotubes promote bone mitosis and histogenesis, primary calvariae osteoblastic cells

Wojtek Tutak

2010-01-01

294

Growth of Horizontally-Aligned Single-Walled Carbon Nanotubes on Sapphire Surface by Needle-Scratching Method  

NASA Astrophysics Data System (ADS)

We report the growth of single-walled carbon nanotubes (SWNTs) over metal nanoparticles which are formed by scratching sapphire surface with metal wires. The chemical vapor deposition over sapphire substrate scratched with Fe and Co metal wires gives horizontally aligned SWNTs, while no nanotube growth is observed for Au, Mo, and Ni wires. This result suggests that the nanoparticles scattered from Fe and Co wires act as the catalyst for SWNT growth, being different from the previously proposed substrate-catalyzed reaction mechanism. Further, we study the effects of the flow rates of CH4--H2 gases during the SWNT growth on the nanotube density and diameter.

Ago, Hiroki; Kayo, Yasumichi; Tsuji, Masaharu

2012-04-01

295

A Molecular Dynamics Study on the Exfoliation of Single Walled Carbon Nanotubes in Supercritical Carbon Dioxide  

NASA Astrophysics Data System (ADS)

Carbon nanotubes (CNTs) could be used in various technological applications due to their structural, electrical and mechanical properties. However, in order to get the theoretically predicted benefits, nanotubes have to be succesfully dispersed in the polymer matrix. Supercritical fluids were previously shown to result in good dispersion of nanofillers (in the case of clays and spherical nanofillers). In the current study, we investigated the potential use of supercritical carbon dioxide to unbundle single walled carbon nanotubes via molecular dynamics simulations. Various carbon nanotube systems were simulated with XenoView simulation software, and the effect of surface modification of nanotube with CO2-philic chemicals was investigted on nanotube dispersion. Results showed that surface modification of nanotubes improves their dispersion in supercritical carbon dioxide.

Senturk-Ozer, Semra; Rende, Deniz; Baysal, Nihat; Ozisik, Rahmi

2012-02-01

296

Selective polycarboxylation of semiconducting single-walled carbon nanotubes by reductive sidewall functionalization.  

PubMed

The efficient and controllable synthesis, the detailed characterization, and the chemical postfunctionalization of polycarboxylated single-walled carbon nanotubes SWCNT(COOH)(n) are reported. This innovative covalent sidewall functionalization method is characterized by (a) the preservation of the integrity of the entire ?-framework of SWCNTs; (b) the possibility of achieving very high degrees of addition; (c) control of the functionalization degrees by the variation of the reaction conditions (reaction time, ultrasonic treatment, pressure); (d) the identification of conditions for the selective functionalization of semiconducting carbon nanotubes, leaving unfunctionalized metallic tubes behind; (e) the proof that the introduced carboxylic acid functionalities can serve as versatile anchor points for the coupling to functional molecules; and (f) the application of a subsequent thermal degradation step of the functionalized semiconducting tubes leaving behind intact metallic SWCNTs. Functional derivatives have been characterized in detail by means of Raman, UV-vis/nIR, IR, and fluorescence spectroscopy as well as by thermogravimetric analysis combined with mass spectrometry, atomic force microscopy, and zeta-potential measurements. PMID:22035086

Gebhardt, Benjamin; Hof, Ferdinand; Backes, Claudia; Müller, Matthias; Plocke, Thomas; Maultzsch, Janina; Thomsen, Christian; Hauke, Frank; Hirsch, Andreas

2011-11-10

297

Optical characterization of single-walled carbon nanotubes synthesized by catalytic decomposition of alcohol  

NASA Astrophysics Data System (ADS)

Single-walled carbon nanotubes (SWNTs), synthesized by a catalytic decomposition of alcohol (alcohol CVD method, ACCVD), are compared with high-pressure CO (HiPco) SWNT samples through optical spectroscopic measurements such as resonant Raman scattering, optical absorption and near infrared fluorescence. By the ACCVD method, SWNTs were synthesized either on zeolite catalyst-support particles or directly on the surface of a quartz substrate; in the latter case, a simple dip-coat technique was employed for mounting the metal catalyst. Specific morphological characteristics of as-grown SWNTs generated on zeolite support are presented using SEM and TEM, revealing that the SWNTs produced by the proposed method possess the significant quality of being almost free from amorphous carbons or metal particle impurities. The quality and diameter distribution of SWNTs were investigated and discussed through the results of Raman scattering and optical absorption. The average diameter was slightly smaller for SWNTs grown on zeolite particles than for HiPco SWNTs. Finally, fluorescent emission spectra from isolated SWNTs in an aqueous surfactant suspension were measured for various excitation wavelengths to determine the structural (n,m) distribution of the SWNTs. The narrower chirality distribution for ACCVD SWNTs grown on zeolite compared with HiPco SWNTs was demonstrated.

Maruyama, Shigeo; Miyauchi, Yuhei; Murakami, Yoichi; Chiashi, Shohei

2003-10-01

298

Hydrogen Adsorption in Purified Single Walled Carbon Nanotubes (SWNTs)  

NASA Astrophysics Data System (ADS)

We report results of H2 adsorption in SWNTs (produced by the arc-discharge method and purified), at 77K and moderate pressure (<20 atm.) We characterized the materials by HRTEM, Raman Spectroscopy and N2 adsorption isotherms, in order to determine the morphology and texture of sample for gas storage. HRTEM and temperature programed oxidation (TPO) results showed that the purified samples were clean from amorphous carbon, multishell carbons (MSC) and catalyst particles. In certain cases, HRTEM shows the tubes are in tact, while in other cases, it is observed that openings in the wall are created, and/or the tubes are cut into short tubelets. N2 adsorption studies allow us to obtain the specific surface area (SSA) and approximate pore size distribution. After purification, the SSA increases from ~280 m^2/g to 470 m^2/g. Measurements of H2 adsorption were performed in order to evaluate the adsorption capacity of the nanotubes at 77K and below 20 bar. We found up to 6 wt% H2 adsorbed in our purified material. (Work supported by Honda Motors R&D Co.)

Pradhan, B. K.; Harutyunyan, A. R.; Sumanasekera, G. U.; Eklund, P. C.; Tokune, T.; Fujiwara, Y.

2001-03-01

299

Doping single-walled carbon nanotubes through molecular charge-transfer: a theoretical study.  

PubMed

We study the effect of the molecular charge transfer on the electronic structure of metallic (5,5) and semiconducting (8,0) single-walled carbon nanotubes (SWNTs) induced by surface adsorption of various organic donor-acceptor molecules of different affinities using ab initio density functional theory. Our results, obtained from first-principles spin-polarized calculations show that the adsorption of molecules with different affinities reflects the difference in interaction strength that measure the overall energy of adsorption. Moderate values of the binding energy of these surface adsorbed molecular charge-transfer complexes suggest that the nature of interaction is in the physisorption regime, and mainly governs by Coulombic forces. We also find that the large band gap of semiconducting (8,0) SWNT can be tuned through the surface adsorption of selective organic molecules which gives rise to mid-gap localized molecular levels near the Fermi energy with tuning of band gap region. Interestingly, we find that the metallic (5,5) SWNT and semiconducting (8,0) SWNT turn into semiconducting and metallic nanotubes respectively in presence of selective surface adsorbed molecules, corroborating recent experimental findings. We also suggest that these charge transfer effect can be probed through optical conductivity measurement, as the low-frequency profiles are affected by charge transfer. PMID:20648348

Manna, Arun K; Pati, Swapan K

2010-04-14

300

Single walled carbon nanotube growth and chirality dependence on catalyst composition.  

PubMed

Vertical arrays of single walled carbon nanotubes (VA-SWNTs) were grown using bi-metallic nanoparticle pro-catalysts. Iron oxide particles were doped with varying quantities of first row transition metals (Mn, Co, Ni, and Cu) for a comparative study of the growth of nanotubes. VA-CNT samples were verified using scanning electron microscopy, and characterized using resonance Raman spectroscopy. The length of the VA-CNTs is used as a measure of catalyst activity: the presence of dopants results in a change in the CNT length and length distribution. Cross correlation of the Raman spectra reveal variations in the distribution of radial breathing mode peaks according to the pro-catalyst composition. The formation of various chirality nanotubes is constant between repetitive runs with a particular catalyst, but may be controlled by the identity and concentration of the metal dopants within the iron catalyst. These results demonstrate that the composition of the catalyst is a major driving force toward type selective growth of nanotubes. PMID:23974219

Orbaek, Alvin W; Owens, Andrew C; Crouse, Christopher C; Pint, Cary L; Hauge, Robert H; Barron, Andrew R

2013-09-26

301

Electric field dependence of photoluminescence from individual single-walled carbon nanotubes  

Microsoft Academic Search

Using suspended single-walled carbon nanotubes, we investigate electric field effects on photoluminescence. Trenches are fabricated on SiO2\\/Si substrates, and Pt is deposited for electrical contacts. Carbon nanotubes are grown by patterned chemical vapor deposition. These devices operate as back-gate field effect transistors, allowing application of electric fields on as-grown ultraclean nanotubes. Individual suspended carbon nanotubes are identified by taking photoluminescence

S. Yasukochi; T. Murai; T. Shimada; S. Chiashi; S. Maruyama; Y. K. Kato

2011-01-01

302

Coherently Controlled Ballistic Charge Currents Injected in Single-Walled Carbon Nanotubes and Graphite  

Microsoft Academic Search

Ballistic electrical currents are optically injected into aligned single-walled carbon nanotubes and bulk graphite at 300 K via quantum interference between single and two photon absorption of phase-related 700 and 1400 nm, 150 fs pulses. The transient currents are detected via the emitted terahertz radiation. Optical phase and power dependence are consistent with the quantum interference optical process. Under similar

Ryan W. Newson; Jean-Michel Me?nard; Christian Sames; Markus Betz; Henry M. van Driel

2008-01-01

303

A rod model for three dimensional deformations of single-walled carbon nanotubes  

Microsoft Academic Search

A continuum model for single-walled carbon nanotubes (SWCNT) is presented which is based on an extension to the special Cosserat theory of rods (Kumar and Mukherjee, 2011). The model allows deformation of a nanotube’s lateral surface in a one dimensional framework and hence is an efficient substitute to the commonly used two dimensional shell models for nanotubes. The model predicts

Ajeet Kumar; Subrata Mukherjee; Jeffrey T. Paci; Karthick Chandraseker; George C. Schatz

304

Air separation by single wall carbon nanotubes: Thermodynamics and adsorptive selectivity  

Microsoft Academic Search

Separation of a nitrogen-oxygen mixture (air) by single wall carbon nanotubes has been studied using grand canonical Monte Carlo simulations at a range of nanotube diameters, temperatures, and pressures. It is demonstrated that depending on these operating parameters, the extent of adsorptive selectivity can vary significantly. Detailed calculations are also presented for the adsorption isotherms, energies, and isosteric heats of

Gaurav Arora; Stanley I. Sandler

2005-01-01

305

Dependence of single-walled carbon nanotubes' adsorption kinetics on temperature and binding energy  

Microsoft Academic Search

We present adsorption kinetics results for hydrogen, freon and ethane on single walled carbon nanotubes. We measured the decrease of the pressure as a function of time as equilibrium is approached. Our results indicate that the equilibration time is a function of?T; where? is the binding energy of adsorbate and T is the isotherm temperature. We also compare the dependence

Vaiva Krungleviciute; Dinesh Rawat; Murat Bulut; Luke Heroux; Aldo Migone

2007-01-01

306

Measurement Issues in Single Wall Carbon Nanotubes (NIST Recommended Practice Guide).  

National Technical Information Service (NTIS)

The NIST Recommended Practice Guide on Measurement Issues in 'Single Wall Carbon Nanotubes' represents the output from the 2nd NASA-NIST workshop devoted to issues of nanotube purity, dispersion and measurement techniques held at NIST in 2005. In attendan...

K. Migler S. Arepalli S. Freiman S. Hooker

2008-01-01

307

Interfacial in situ polymerization of single wall carbon nanotube\\/nylon 6,6 nanocomposites  

Microsoft Academic Search

An interfacial polymerization method for nylon 6,6 was adapted to produce nanocomposites with single wall carbon nanotubes (SWNT) via in situ polymerization. SWNT were incorporated in purified, functionalized or surfactant stabilized forms. The functionalization of SWNT was characterized by FTIR, Raman spectroscopy and TGA and the SWNT dispersion was characterized by optical microscopy before and after the in situ polymerization.

Reto Haggenmueller; Fangming Du; John E. Fischer; Karen I. Winey

2006-01-01

308

Surface chemical functionalized single-walled carbon nanotube with anchored phenol structures: Physical and chemical characterization  

Microsoft Academic Search

Surface functionalization of single-walled carbon nanotube was carried out by introducing ylides groups containing anchored phenol structures. The functionalized nanotube is characterized using elemental analysis, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, thermogravimetric analysis, Raman spectroscopy and zeta potential measurements. Elemental and FT-IR analysis reveal the successful functionalization of azomethine ylides. Raman spectroscopic studies corroborates that the surface

Jong Hyun Bae; A. M. Shanmugharaj; Woo Hyun Noh; Won Seok Choi; Sung Hun Ryu

2007-01-01

309

Thermogravimetric analysis of single-wall carbon nanotubes ultrasonicated in monochlorobenzene  

Microsoft Academic Search

The single-wall carbon nanotubes (SWNTs) purified by nitric acid were ultrasonicated in monochlorobenzene solution. Thermogravimetric analysis complemented by transmission electron microscopy and Raman spectroscopy was used to analyze the thus ultrasonicated SWNTs. The results show that two kinds of modified SWNTs and one modification-free SWNT coexist in ultrasonicated SWNTs and burned in three different temperature ranges. The different chemical modifications

Minfang Zhang; Masako Yudasaka; Akira Koshio; Sumio Iijima

2002-01-01

310

Aligned single-wall carbon nanotubes in composites by melt processing methods  

Microsoft Academic Search

This Letter describes the production of single-wall carbon nanotube (SWNT) – polymer composites with enhanced mechanical and electrical properties and exceptional nanotube alignment. A combination of solvent casting and melt mixing was used to disperse SWNT materials in poly(methyl methacrylate) (PMMA). Composite films showed higher conductivity along the flow direction than perpendicular to it. Composite fibers were melt spun to

R. Haggenmueller; H. H. Gommans; A. G. Rinzler; J. E. Fischer; K. I. Winey

2000-01-01

311

Processing, spinning, and fabrication of continuous fibers of single-walled carbon nanotubes  

Microsoft Academic Search

Single-walled carbon nanotubes (SWNTs) show great promise for use in a wide range of applications. One of the most promising avenues for attaining these applications is the dispersion of SWNTs at high concentrations in superacids and processing into macroscopic articles such as fibers or films. Fibers spun from SWNT\\/superacid dispersions indicate that the morphology of the starting SWNT material influences

Richard Delane Booker

2010-01-01

312

Disorder Induced Triple Resonant Raman Phenomena in Single-Wall Carbon Nanotubes  

Microsoft Academic Search

The disorder induced D band and its overtone, the D* band (not disorder induced, sometimes also called G') in the Raman spectrum of single wall carbon nanotubes (SWCNTs) were investigated theoretically and experimentally. The measured peak positions vs. laser excitation energy (Elaser) exhibit an oscillation superimposed on a linear shift. We have shown theoretically that the D-band intensity of an

J. Kürti; V. Zólyomi; A. Grüneis; H. Kuzmany

2002-01-01

313

Disorder Induced Triple Resonant Raman Phenomena in Single-Wall Carbon Nanotubes  

Microsoft Academic Search

The disorder induced D band and its overtone, the D* band (not disorder induced, sometimes also called G’) in the Raman spectrum of single wall carbon nanotubes (SWCNTs) were investigated theoretically and experimentally. The measured peak positions vs. laser excitation energy (Elaser) exhibit an oscillation superimposed on a linear shift. We have shown theoretically that the D-band intensity of an

V. Zo´lyomi; H. Kuzmany

2002-01-01

314

Length dependence of critical measures in single-walled carbon nanotubes  

Microsoft Academic Search

This paper presents an investigation on the buckling behaviour of single-walled carbon nanotubes under various loading conditions (compression, bending and torsion) and unveils several aspects concerning the dependence of critical measures (axial strain, bending curvature and twisting angle) on the nanotube length. The buckling results are obtained by means of an atomistic-scale generalized beam theory (GBT) that incorporates local deformation

N. Silvestre

2008-01-01

315

Crosslinked polymer sheaths for dispersing individual single-walled carbon nanotubes in nonaqueous solvents  

NASA Astrophysics Data System (ADS)

Single-walled carbon nanotubes have been suspended individually in water by encasing them in a thin, uniform layer of the crosslinkable polymer poly (N-vinylpyrrolidone-co-allylamine). When this polymer is crosslinked under dilute conditions, the polymer sheath, formerly stabilized by the hydrophobic effect, becomes stable to changes in the solvent system.

Ojha, L. R.; Tchoul, M. N.; Bastola, K. P.; Ausman, K. D.

2013-11-01

316

Production of vertical arrays of small diameter single-walled carbon nanotubes  

DOEpatents

A hot filament chemical vapor deposition method has been developed to grow at least one vertical single-walled carbon nanotube (SWNT). In general, various embodiments of the present invention disclose novel processes for growing and/or producing enhanced nanotube carpets with decreased diameters as compared to the prior art.

Hauge, Robert H; Xu, Ya-Qiong

2013-08-13

317

Structural and electronic properties of alkali-doped single-walled carbon nanotubes  

Microsoft Academic Search

In this thesis, we study the properties of alkali doped single walled carbon nanotubes (SWNT). SWNT are crystallized into ropes, which display the one-dimensional electronic properties of the constituent nanotubes. Using x-ray diffraction, we show that the alkali atoms invade the channels in the triangular rope lattice and determine the structure of the doped ropes. We show that the diffraction

Norbert Marcel Nemes

2002-01-01

318

Specific heat of Single-Walled Carbon Nanotubes: A Lattice Dynamics Study  

Microsoft Academic Search

In terms of the symmetry of single-walled carbon nanotubes, we present a two-atom unit cell model to study the lattice dynamics and the thermal properties. Different behavior of size dependence of specific heat is found at different temperature. At low temperature, it is found that the specific heat is proportional to the tubule diameter. However, at high temperature the specific

J. X. Cao; X. H. Yan; Y. Xiao

2003-01-01

319

Single-wall carbon nanotubes phonon spectra: Symmetry-based calculations  

Microsoft Academic Search

The phonon dispersions and atomic displacements for single-wall carbon nanotubes of arbitrary chirality are calculated. The full symmetry is implemented. The approach is based on the force constants of graphene, with the symmetry imposed modifications providing the twisting acoustic mode exactly. The functional dependence of frequencies of the Raman and infrared active modes on the wrapping angle and on the

E. Dobardzic; I. Milosevic; B. Nikolic; T. Vukovic; M. Damnjanovic

2003-01-01

320

Adsorption of He atoms in external grooves of single-wall carbon nanotube bundles  

Microsoft Academic Search

I calculate the quantum states for He atom in the potential of an external groove of the single-wall carbon nanotube bundle. The calculated ground-state energy is found to be in fair agreement with the experimental estimate which suggests that the outer groove site is a preferential site for the adsorption of He gas in the samples studied experimentally. I also

Antonio Siber

2002-01-01

321

Selective Solubilisation of Single Walled Carbon Nanotubes Using Polycyclic Aromatic Hydrocarbons  

Microsoft Academic Search

Single-walled carbon nanotubes (SWCNTS) are proposed to be one of the most promising nanomaterials, with unique electronic and mechanical properties which lend themselves to a variety of applications. In all cases the quality of the SWCNT material is important, and for some applications it is paramount. Despite sustained efforts, all currently known SWCNT synthetic techniques generate significant quantities of impurities.

Sourabhi Debnath

2010-01-01

322

Characterization of single wall carbon nanotubes by means of rare gas adsorption  

Microsoft Academic Search

Based on the formalisms of Langmuir and Fowler, theoretical adsorption isotherms are calculated for different bundle geometries of single wall carbon nanotubes in a triangular lattice. The authors show the dependence of the adsorption properties on the nanotube diameter and on the specific morphology of the bundles they constitute. The authors demonstrate how isotherm curve analysis can help to experimentally

M. Arab; F. Picaud; C. Ramseyer; M. R. Babaa; F. Valsaque; E. McRae

2007-01-01

323

MICROWAVE-INDUCED RAPID CHEMICAL FUNCTIONALIZATION OF SINGLE-WALLED CARBON NANOTUBES (R830901)  

EPA Science Inventory

Abstract The microwave-induced chemical functionalization of single-walled carbon nanotubes (SWNTs) is reported. The major advantage of this high-energy procedure is that it reduced the reaction time to the order of minutes and the number of steps in the reac...

324

Exciton Diffusion in Air-Suspended Single-Walled Carbon Nanotubes  

Microsoft Academic Search

Direct measurements of the diffusion length of excitons in air-suspended single-walled carbon nanotubes are reported. Photoluminescence microscopy is used to identify individual nanotubes and to determine their lengths and chiral indices. Exciton diffusion length is obtained by comparing the dependence of photoluminescence intensity on the nanotube length to numerical solutions of diffusion equations. We find that the diffusion length in

S. Moritsubo; T. Murai; T. Shimada; Y. Murakami; S. Chiashi; S. Maruyama; Y. K. Kato

2010-01-01

325

Shell Filling in Closed Single-Wall Carbon Nanotube Quantum Dots  

Microsoft Academic Search

We observe twofold shell filling in the spectra of closed one-dimensional quantum dots formed in single-wall carbon nanotubes. Its signatures include a bimodal distribution of addition energies, correlations in the excitation spectra for different electron number, and alternation of the spins of the added electrons. This provides a contrast with quantum dots in higher dimensions, where such spin pairing is

David H. Cobden; Jesper Nygård

2002-01-01

326

Quantification of thin graphene sheets contained in spherical aggregates of single-walled carbon nanohorns  

Microsoft Academic Search

Spherical aggregates of single-walled carbon nanohorns (SWNHs) produced by CO2 laser ablation of graphite contain thin graphene sheets (TGSs), and their quantities depend on formation conditions. To adjust laser ablation condition to increase TGS quantities, TGS quantification in products is necessary; however, its method has not been established. We have found that high resolution thermogravimetric analysis (HRTGA) showed SWNHs and

Michiko Irie; Maki Nakamura; Minfang Zhang; Ryota Yuge; Sumio Iijima; Masako Yudasaka

2010-01-01

327

Transport of Single-Walled Carbon Nanotubes in Porous Media: Filtration Mechanisms and Reversibility  

Microsoft Academic Search

Deposition of nanomaterials onto surfaces is a key process governing their transport, fate, and reactivity in aquatic systems. We evaluated the transport and deposition behavior of carboxyl functionalized single-walled carbon nanotubes (SWNTs) in a well-defined porous medium composed of clean quartz sand over a range of solution chemistries. Our results showthatincreasingsolutionionicstrengthoradditionofcalcium ions result in increased SWNT deposition (filtration). This observation

DEB P. J AISI; NAVID B. S ALEH; RUTH E. B LAKE; MENACHEM E LIMELECH

328

An energy-equivalent model on studying the mechanical properties of single-walled carbon nanotubes  

Microsoft Academic Search

In this paper, an energy-equivalent model is put forward for studying the mechanical properties of single-walled carbon nanotubes (SWCNTs). The equivalent Young's modulus and shear modulus for both armchair and zigzag SWCNTs are derived by combining the methods of molecular mechanics and continuum mechanics. On the one hand, based on the principle of molecular mechanics, the total system potential energy

Yongdong Wu; Xiaochun Zhang; A. Y. T. Leung; Weifang Zhong

2006-01-01

329

Flexible, transparent single-walled carbon nanotube transistors with graphene electrodes  

Microsoft Academic Search

This paper reports a mechanically flexible, transparent thin film transistor that uses graphene as a conducting electrode and single-walled carbon nanotubes (SWNTs) as a semiconducting channel. These SWNTs and graphene films were printed on flexible plastic substrates using a printing method. The resulting devices exhibited a mobility of ~ 2 cm2 V - 1 s - 1, On\\/Off ratio of

Sukjae Jang; Houk Jang; Youngbin Lee; Daewoo Suh; Seunghyun Baik; Byung Hee Hong; Jong-Hyun Ahn

2010-01-01

330

Crosslinked polymer sheaths for dispersing individual single-walled carbon nanotubes in nonaqueous solvents.  

PubMed

Single-walled carbon nanotubes have been suspended individually in water by encasing them in a thin, uniform layer of the crosslinkable polymer poly (N-vinylpyrrolidone-co-allylamine). When this polymer is crosslinked under dilute conditions, the polymer sheath, formerly stabilized by the hydrophobic effect, becomes stable to changes in the solvent system. PMID:24076577

Ojha, L R; Tchoul, M N; Bastola, K P; Ausman, K D

2013-09-27

331

Solution Casting and Transfer Printing Single-Walled Carbon Nanotube Films  

Microsoft Academic Search

This paper presents methods for solution casting and transfer printing collections of individual single-walled carbon nanotubes (SWNTs) onto a wide range of substrates, including plastic sheets. The deposition involves introduction of a solvent that removes surfactant from a suspension of SWNTs as it is applied to a substrate. The subsequent controlled flocculation (cF) produces films of SWNTs with densities that

Matthew A. Meitl; Yangxin Zhou; Anshu Gaur; Seokwoo Jeon; Monica L. Usrey; Michael S. Strano; John A. Rogers

2004-01-01

332

Scaling Properties in Transistors That Use Aligned Arrays of Single-Walled Carbon Nanotubes  

Microsoft Academic Search

Recent studies and device demonstrations indicate that horizontally aligned arrays of linearly configured single-walled carbon nanotubes (SWNTs) can serve as an effective thin film semiconductor material, suitable for scalable use in high-performance transistors. This paper presents the results of systematic investigations of the dependence of device properties on channel length, to reveal the role of channel and contact resistance in

Xinning Ho; Lina Ye; Slava V. Rotkin; Qing Cao; Sakulsuk Unarunotai; Shuaib Salamat; Muhammad A. Alam; John A. Rogers

2010-01-01

333

Single walled carbon nano-tube, ferroelectric liquid crystal composites: Excellent diffractive tool  

Microsoft Academic Search

We present a switchable grating based on chiral single walled carbon nano-tube (SWCNT) doped ferroelectric liquid crystals (FLCs). The presence of SWCNTs improves the diffraction profile of the pure FLC. The diffraction efficiency, i.e., the ratio of intensities of first order and zero order maxima is more than 100% for the higher concentration of SWCNTs in pure FLC. This phenomenon

A. K. Srivastava; E. P. Pozhidaev; V. G. Chigrinov; R. Manohar

2011-01-01

334

Range Analysis on the Wave Propagation Properties of a Single Wall Carbon Nano Tube  

Microsoft Academic Search

In this paper consistent bounds of the wave propagation properties concerning a Single Wall Carbon NanoTube (SWCNT) modeled as a Transmission Line are assessed. The monotonic inclusion property of the Interval Analysis leads to guaranteed limits for the given characteristics when the model parameters are uncertain. The common mode wave propagation in a SWCNT is considered and the variability range

B. de Vivo; L. Egiziano; P. Lamberti; V. Tucci

2008-01-01

335

Graphene nanoribbons produced by the oxidative unzipping of single-wall carbon nanotubes  

Microsoft Academic Search

Graphene nanoribbons were synthesized by oxidative unzipping of single-wall carbon nanotubes (SWCNTs). The nanoribbons produced from SWCNTs were characterized using FT-IR, Raman and X-ray photoelectron spectroscopy. For the morphological study of the product obtained from the SWCNT unzipping reaction, transmission electron microscopy and atomic force microscopy were used, confirming the typical graphene nanoribbon structure.

Franco Cataldo; Giuseppe Compagnini; Giacomo Patané; Ornella Ursini; Giancarlo Angelini; Primoz Rebernik Ribic; Giorgio Margaritondo; Antonio Cricenti; Giuseppe Palleschi; Federica Valentini

2010-01-01

336

Optical studies of single wall carbon nanotubes upon photodoping and electrochemical doping  

Microsoft Academic Search

The reflectivity, absorption, and resonant Raman scattering spectra of single wall carbon nanotubes (SWCNT) in vacuum filtered free standing films (papers) and drop-cast films were studied in the visible and infrared regions. The effects of electrochemical doping on the Raman scattering and reflectivity spectra of papers were studied in aqueous solutions at applied biases of -2V to 2V. Reversible, asymmetric

W. Joshua Kennedy; Z. Valy Vardeny; Ray H. Baughman; Anvar A. Zakhidov; Alan B. Dalton

2003-01-01

337

Influence of chamber volume in single-walled carbon nanotube synthesis by an electric arc  

Microsoft Academic Search

Single-walled carbon nanotubes (SWCNTs) were produced by an electric arc process in a low-pressure chamber with vertical electrodes using heterogeneous graphite anodes containing nickel and yttrium catalysts. The influence of the chamber volume (18, 25 and 60 L) and graphite grain size (1 and 100 µm) of the anode on the resulting products was analysed. This was correlated with the

V Ramarozatovo; A Mansour; M Razafinimanana; M Monthioux; F Valensi; L Noé; M Masquère

2012-01-01

338

Panchromatic light harvesting in single wall carbon nanotube hybrids-immobilization of porphyrin-phthalocyanine conjugates.  

PubMed

We report on immobilizing H(2)/Zn-porphyrin-Zn-phthalocyanine conjugates onto single wall carbon nanotubes and by using the excellent stability of the resulting suspensions we were able to demonstrate for the first time the sequence of energy transfer-electron transfer in SWNT donor-acceptor conjugates. PMID:21301742

Bartelmess, Juergen; Soares, Ana R M; Martínez-Díaz, M Victoria; Neves, Maria G P M S; Tomé, Augusto C; Cavaleiro, José A S; Torres, Tomás; Guldi, Dirk M

2011-02-08

339

Engineered Carbohydrate-Binding Module (CBM) Protein-Suspended Single-Walled Carbon Nanotubes in Water  

SciTech Connect

Engineered protein, CtCBM4, the first carbohydrate-binding module (CBM) protein is successfully used to debundle and suspend single-walled carbon nanotubes (SWNTs) effectively in aqueous solution, which opens up a new avenue in further functionalizing and potential selectively fractionating SWNTs for diverse biology- and/or energy-related applications.

Xu,Q.; Song, Q.; Ai, X.; McDonald, T. J.; Long, H.; Ding. S. Y.; Himmel, M. E.; Rumbles, G.

2009-01-01

340

Single-Walled Carbon Nanotubes Targeted to the Tumor Vasculature for Breast Cancer Treatment.  

National Technical Information Service (NTIS)

Annexin V has been produced in good purity and high yield has been shown to bind strongly to plastic-immobilized phosphatidylserine (PS). Annexin V was conjugated with a suspension of single-walled carbon nanotubes (SWNTs) and carboxymethyl- cellulose (CM...

R. Harrison

2008-01-01

341

Engineered carbohydrate-binding module (CBM) protein-suspended single-walled carbon nanotubes in water.  

PubMed

Engineered protein, CtCBM4, the first carbohydrate-binding module (CBM) protein is successfully used to debundle and suspend single-walled carbon nanotubes (SWNTs) effectively in aqueous solution, which opens up a new avenue in further functionalizing and potential selectively fractionating SWNTs for diverse biology- and/or energy-related applications. PMID:19209321

Xu, Qi; Song, Qing; Ai, Xin; McDonald, Timothy J; Long, Hai; Ding, Shi-You; Himmel, Michael E; Rumbles, Garry

2008-11-21

342

Thermal conductance of single-walled carbon nanotube embedded in an elastic half-space  

NASA Astrophysics Data System (ADS)

Calculations of ballistic thermal conductance of single-walled carbon nanotube (CNT) embedded in an elastic half-space are presented. The conductance is very different than the conductance of freestanding CNT due to change in phonon velocity and maximum cutoff frequency. Depending on the temperature, the conductance of embedded CNT can be higher or lower than that of freestanding CNT. Applications of the formulation are in CNT-based nanocomposites or CNT in contact with an elastic substrate. Good agreement with experimental thermal conductivity of nanocomposites made from single-walled CNT and epoxy is found.

Prasher, Ravi

2007-04-01

343

Preparation and characterization of sulfonic acid-functionalized single-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

A strategy for the functionalization of single-walled carbon nanotubes is reported. The synthesis involved the conversion of fluorinated single-walled carbon nanotubes to the thiolated derivative assisted by phosphorous pentasulfide. The thiol group is then quantitatively oxidized to the sulfonic acid group. The extent of oxidation of the thiol precursor is confirmed using X-ray photoelectron spectroscopy, which proved to be immensely useful to discriminate between the -SH and -SO3H with a chemical shift for the sulfur 2p (approx. 5 eV). The functionalized carbon nanotubes were further characterized by infrared spectroscopy, thermogravimetric analysis, and transmission electron microscopy which revealed a significant change in morphology between the fluoro carbon nanotubes, the thiol and sulfonic acid-modified carbon nanotubes.

Adams, Luqman; Oki, Aderemi; Grady, Tony; McWhinney, Hylton; Luo, Zhiping

2009-02-01

344

In situ mass spectroscopic analysis of alcohol catalytic chemical vapor deposition process for single-walled carbon nanotube  

NASA Astrophysics Data System (ADS)

In situ mass spectroscopic analysis was carried out to clarify the growth mechanism of single-walled carbon nanotube grown by alcohol catalytic chemical vapor deposition. When catalysts were used, pyrolysis could be accomplished at a temperature of 600 °C; without the use of catalysts, successful pyrolysis required a temperature of more than 800 °C. Ethylene and acetylene are important products for the synthesis of carbon nanotubes, and fusion of the metal catalyst is the cause of failure of synthesis at high temperatures. This fact indicates that the degradation and polymerization of ethanol are not the cause of the failure of synthesis.

Tomie, Takashi; Inoue, Shuhei; Iba, Yushi; Matsumura, Yukihiko

2012-05-01

345

Nanocatalyst structure as a template to define chirality of nascent single-walled carbon nanotubes.  

PubMed

Chirality is a crucial factor in a single-walled carbon nanotube (SWCNT) because it determines its optical and electronic properties. A chiral angle spanning from 0° to 30° results from twisting of the graphene sheet conforming the nanotube wall and is equivalently expressed by chiral indexes (n,m). However, lack of chirality control during SWCNT synthesis is an obstacle for a widespread use of these materials. Here we use first-principles density functional theory (DFT) and classical molecular dynamics (MD) simulations to propose and illustrate basic concepts supporting that the nanocatalyst structure may act as a template to control the chirality during nanotube synthesis. DFT optimizations of metal cluster (Co and Cu)?cap systems for caps of various chiralities are used to show that an inverse template effect from the nascent carbon nanostructure over the catalyst may exist in floating catalysts; such effect determines a negligible chirality control. Classical MD simulations are used to investigate the influence of a strongly interacting substrate on the structure of a metal nanocatalyst and illustrate how such interaction may help preserve catalyst crystallinity. Finally, DFT optimizations of carbon structures on stepped (211) and (321) cobalt surfaces are used to demonstrate the template effect imparted by the nanocatalyst surface on the growing carbon structure at early stages of nucleation. It is found that depending on the step structure and type of building block (short chains, single atoms, or hexagonal rings), thermodynamics favor armchair or zigzag termination, which provides guidelines for a chirality controlled process based on tuning the catalyst structure and the type of precursor gas. PMID:21219018

Gómez-Gualdrón, Diego A; Zhao, Jin; Balbuena, Perla B

2011-01-01

346

Collision dynamics of energetic carbon ions impinging on single-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

By employing atomistic simulations based on an empirical potential, we study the collision dynamics of low-energy carbon ions impinging on single-walled carbon nanotubes. We investigate the energy transferred from the incident carbon ions to the target atoms in the nanotubes. We find that the lowest incident energy needed for the primary knock-on atom to be permanently displaced from its original location is 18 eV, and for the secondary knock-on atom to escape out of the nanotube is estimated to be 28 eV. Moreover, we find that the incident threshold energy strongly depends on the diameter of the nanotube and its chirality, and saturates towards the corresponding value in graphene as the tube diameter increases. Furthermore, a single vacancy and an adatom defects are obtained after optimization using the ab-initio calculations.

Zhang, Chao; Mao, Fei; Zhang, Feng-Shou

2013-10-01

347

Enhanced adsorption of mercury ions on thiol derivatized single wall carbon nanotubes.  

PubMed

Thiol-derivatized single walled carbon nanotube (SWCNT-SH) powders were synthesized by reacting acid-cut SWCNTs with cysteamine hydrochloride using carbodiimide coupling. Infrared (IR) spectroscopy, Raman spectroscopy and thermogravimetric analysis confirmed the successful functionalization of the SWCNTs. SWCNT-SH powders exhibited a threefold higher adsorption capacity for Hg(II) ions compared to pristine SWCNTs, and a fourfold higher adsorption capacity compared to activated carbon. The influence of adsorption time, pH, initial metal concentration and adsorbent dose on Hg(II) ion removal was investigated. The maximum adsorption capacity of the SWCNT-SH powders was estimated by using equilibrium isotherms, such as Freundlich and Langmuir, and the maximum adsorption capacity of the SWCNT-SH powder was found to be 131mg/g. A first-order rate model was employed to describe the kinetic adsorption process of Hg(II) ions onto the SWCNT-SH powders. Desorption studies revealed that Hg(II) ions could be easily removed from the SWCNT-SH powders by altering the pH. Further, the adsorption efficiency of recovered SWCNT-SH powders was retained up to 91%, even after 5 adsorption/desorption cycles. PMID:23994651

Bandaru, Narasimha Murthy; Reta, Nekane; Dalal, Habibullah; Ellis, Amanda V; Shapter, Joseph; Voelcker, Nicolas H

2013-08-08

348

Chirality-dependent vapor-phase epitaxial growth and termination of single-wall carbon nanotubes.  

PubMed

Structurally uniform and chirality-pure single-wall carbon nanotubes are highly desired for both fundamental study and many of their technological applications, such as electronics, optoelectronics, and biomedical imaging. Considerable efforts have been invested in the synthesis of nanotubes with defined chiralities by tuning the growth recipes but the approach has only limited success. Recently, we have shown that chirality-pure short nanotubes can be used as seeds for vapor-phase epitaxial cloning growth, opening up a new route toward chirality-controlled carbon nanotube synthesis. Nevertheless, the yield of vapor-phase epitaxial growth is rather limited at the present stage, due in large part to the lack of mechanistic understanding of the process. Here we report chirality-dependent growth kinetics and termination mechanism for the vapor-phase epitaxial growth of seven single-chirality nanotubes of (9, 1), (6, 5), (8, 3), (7, 6), (10, 2), (6, 6), and (7, 7), covering near zigzag, medium chiral angle, and near armchair semiconductors, as well as armchair metallic nanotubes. Our results reveal that the growth rates of nanotubes increase with their chiral angles while the active lifetimes of the growth hold opposite trend. Consequently, the chirality distribution of a nanotube ensemble is jointly determined by both growth rates and lifetimes. These results correlate nanotube structures and properties with their growth behaviors and deepen our understanding of chirality-controlled growth of nanotubes. PMID:23937554

Liu, Bilu; Liu, Jia; Tu, Xiaomin; Zhang, Jialu; Zheng, Ming; Zhou, Chongwu

2013-08-23

349

Spectroelectrochemical properties of the single walled carbon nanotubes functionalized with polydiphenylamine doped with heteropolyanions  

NASA Astrophysics Data System (ADS)

A combined chemical-electrochemical method was used for covalent functionalization of single-walled carbon nanotube (SWNT) with polydiphenylamine (PDPA) doped with heteropolyanions of H3PMo12O40·xH2O. The functionalization process induces in Raman spectra of SWNTs the following changes: (i) an increase in relative intensity of the D band, accompanied a gradual up-shift of the G band in the case of the semiconducting tubes and a decrease in the relative intensity of band peaked at 1540 cm-1 is remarked in the case of the metallic tubes; (ii) in the anti-Stokes Raman spectrum an increase in the relative intensity of Raman line of metallic tubes peaked at -1560 cm-1 is remarked when the cycles number increases. The additional down-shift of the FTIR bands belonging to H3PMo12O40 heteropolyanions (at 881, 943 and 1055 cm-1) and PDPA (at 688, 736 and 1016 cm-1) originates in hindrance steric effects induced the covalent functionalization of SWNTs with polymer molecules. Using Raman scattering and FTIR spectroscopy we demonstrate that chemical polymerization of diphenylamine in the presence of H3PMo12O40·xH2O and SWNTs results in a composite of the type blend based on PDPA in un-doped state and SWNTs doped with H3PMo12O40 heteropolyanions.

Smaranda, I.; Baibarac, M.; Baltog, I.; Mevellec, J. Y.; Lefrant, S.

2013-01-01

350

Single-walled carbon nanotube/polyaniline/n-silicon solar cells: fabrication, characterization, and performance measurements.  

PubMed

Carbon nanotube-silicon solar cells are a recently investigated photovoltaic architecture with demonstrated high efficiencies. Silicon solar-cell devices fabricated with a thin film of conductive polymer (polyaniline) have been reported, but these devices can suffer from poor performance due to the limited lateral current-carrying capacity of thin polymer films. Herein, hybrid solar-cell devices of a thin film of polyaniline deposited on silicon and covered by a single-walled carbon nanotube film are fabricated and characterized. These hybrid devices combine the conformal coverage given by the polymer and the excellent electrical properties of single-walled carbon nanotube films and significantly outperform either of their component counterparts. Treatment of the silicon base and carbon nanotubes with hydrofluoric acid and a strong oxidizer (thionyl chloride) leads to a significant improvement in performance. PMID:23322677

Tune, Daniel D; Flavel, Benjamin S; Quinton, Jamie S; Ellis, Amanda V; Shapter, Joseph G

2013-01-15

351

Highly efficient exfoliation of individual single-walled carbon nanotubes by biocompatible phenoxylated dextran  

NASA Astrophysics Data System (ADS)

Highly efficient exfoliation of individual single-walled carbon nanotubes (SWNTs) was successfully demonstrated by utilizing biocompatible phenoxylated dextran, a kind of polysaccharide, as a SWNT dispersion agent. Phenoxylated dextran shows greater ability in producing individual SWNTs from raw materials than any other dispersing agent, including anionic surfactants and another polysaccharide. Furthermore, with this novel polymer, SWNT bundles or impurities present in raw materials are removed under much milder processing conditions compared to those of ultra-centrifugation procedures. There exists an optimal composition of phenoxy groups (~13.6 wt%) that leads to the production of high-quality SWNT suspensions, as confirmed by UV-vis-nIR absorption and nIR fluorescence spectroscopy. Furthermore, phenoxylated dextran strongly adsorbs onto SWNTs, enabling SWNT fluorescence even in solid-state films in which metallic SWNTs co-exist. By bypassing ultra-centrifugation, this low-energy dispersion scheme can potentially be scaled up to industrial production levels.Highly efficient exfoliation of individual single-walled carbon nanotubes (SWNTs) was successfully demonstrated by utilizing biocompatible phenoxylated dextran, a kind of polysaccharide, as a SWNT dispersion agent. Phenoxylated dextran shows greater ability in producing individual SWNTs from raw materials than any other dispersing agent, including anionic surfactants and another polysaccharide. Furthermore, with this novel polymer, SWNT bundles or impurities present in raw materials are removed under much milder processing conditions compared to those of ultra-centrifugation procedures. There exists an optimal composition of phenoxy groups (~13.6 wt%) that leads to the production of high-quality SWNT suspensions, as confirmed by UV-vis-nIR absorption and nIR fluorescence spectroscopy. Furthermore, phenoxylated dextran strongly adsorbs onto SWNTs, enabling SWNT fluorescence even in solid-state films in which metallic SWNTs co-exist. By bypassing ultra-centrifugation, this low-energy dispersion scheme can potentially be scaled up to industrial production levels. Electronic supplementary information (ESI) available: Additional spectra (UV-vis-nIR absorption) demonstrating the effect of centrifugation speed, dextran chain length (molecular weight), and dextran concentration on the quality of SWNT suspensions in SDS or P-dextran, the SWNT re-suspension procedure, additional spectra (fluorescence) of fluorescent freeze-dried P-dextran-SWNT suspensions. See DOI: 10.1039/c3nr01352a

Kwon, Taeyun; Lee, Gyudo; Choi, Hyerim; Strano, Michael S.; Kim, Woo-Jae

2013-07-01

352

Collision of hydrogen atom with single-walled carbon nanotube: Adsorption, insertion, and healing  

Microsoft Academic Search

Interaction of hydrogen atom with (5, 5) single-walled carbon nanotube (SWNT) has been studied over the collision energy range from 1 to 30 eV using a molecular dynamics simulation method. In the energy interval of 1-3 eV, the hydrogen atom can be chemisorbed on the outer wall of the SWNT, provided the impact point is near a vertex carbon atom

Yuchen Ma; Yueyuan Xia; Mingwen Zhao; Minju Ying; Xiangdong Liu; Pijun Liu

2001-01-01

353

Atypical Dependence of Electroosmotic Transport on Surface Charge in a Single-wall Carbon Nanotube  

Microsoft Academic Search

Electroosmotic phenomena is widely used to transport and mix fluids in micro- and nanoscale lab-on-a-chip applications. A single-wall carbon nanotube is a promising candidate for nanofluidic applications because of its extraordinary mechanical, electronic, and chemical properties. In this paper, we report on molecular dynamics simulation of electroosmotic transport of NaCl solution through a 5.42 nm diameter carbon nanotube with different

R. Qiao; N. R. Aluru

2003-01-01

354

Derivatization of single-walled carbon nanotubes with redox mediator for biocatalytic oxygen electrodes  

Microsoft Academic Search

Single-walled carbon nanotubes (SWCNTs) were covalently modified with a redox mediator derived from 2,2?-azino-bis-(3-ethylbenzothiazoline)-6-sulfonic acid (ABTS), and implemented in the construction of electrodes for biocatalytic oxygen reduction. The procedure is based on: covalent bonding of mediator to nanotubes, placing the nanotubes directly on the carbon electrode surface and covering the nanostructured electrode with a Nafion film containing laccase as the

K. Sadowska; K. Stolarczyk; J. F. Biernat; K. P. Roberts; J. Rogalski; R. Bilewicz

2010-01-01

355

Confined propagation of covalent chemical reactions on single-walled carbon nanotubes  

Microsoft Academic Search

Covalent chemistry typically occurs randomly on the graphene lattice of a carbon nanotube because electrons are delocalized over thousands of atomic sites, and rapidly destroys the electrical and optical properties of the nanotube. Here we show that the Billups--Birch reductive alkylation, a variant of the nearly century-old Birch reduction, occurs on single-walled carbon nanotubes by defect activation and propagates exclusively

Shunliu Deng; Yin Zhang; Alexandra H. Brozena; Maricris Lodriguito Mayes; Parag Banerjee; Wen-An Chiou; Gary W. Rubloff; George C. Schatz; Yuhuang Wang

2011-01-01

356

Influence of single-walled carbon nanotubes on microbial availability of phenanthrene in sediment  

Microsoft Academic Search

Increasing production and use of single-walled carbon nanotubes (SWCNT) will inevitably lead to release of these nanoparticles\\u000a to aquatic ecosystems. Similar to black carbon (BC) particles, SWCNT have a high affinity for hydrophobic organic contaminants\\u000a (HOCs) and therefore the presence of SWCNT in sediment may lead to altered bioavailability of HOCs. We compared SWCNT with\\u000a biochar and charcoal on their

X. Y. Cui; F. Jia; Y. X. Chen; J. Gan

357

Poly(Butylene Terephthalate)\\/Single Wall Carbon Nanotubes Composite Nanofibers by Electrospinning  

Microsoft Academic Search

Poly(buthylene terephthalate)(PBT)\\/single wall carbon nanotubes (SWCNTs) composite nanofibers were prepared by electrospinning. The effect of carbon nanotubes on the morphology, crystallization, and mechanical properties of the electrospun composite nanofibers were investigated by SEM, DSC, and tensile testing, respectively. SEM observations indicated that the presence of SWCNTs resulted in finer nanofibers for lower loading; however, a broader distribution, especially for the

Omid Saligheh; Rouhollah Arasteh; Mehdi Forouharshad; Reza Eslami Farsani

2011-01-01

358

Single-walled carbon nanotube synthesis using ferrocene and iron pentacarbonyl in a laminar flow reactor  

Microsoft Academic Search

A gas-phase process of single-walled carbon nanotube (SWCNT) formation, based on thermal decomposition of iron pentacarbonyl or ferrocene in the presence of carbon monoxide (CO), was investigated in ambient pressure laminar flow reactors in the temperature range of 600–1300°C. Ferrocene was found to be a better catalyst precursor in the studied conditions since iron pentacarbonyl decomposes at lower temperatures resulting

Anna Moisala; Albert G. Nasibulin; David P. Brown; Hua Jiang; Leonid Khriachtchev; Esko I. Kauppinen

2006-01-01

359

Fabrication of spintronics device by direct synthesis of single-walled carbon nanotubes from ferromagnetic electrodes  

NASA Astrophysics Data System (ADS)

We describe an alternative method for realizing a carbon nanotube spin field-effect transistor device by the direct synthesis of single-walled carbon nanotubes (SWNTs) on substrates by alcohol catalytic chemical vapor deposition. We observed hysteretic magnetoresistance (MR) at low temperatures due to spin-dependent transport. In these devices, the maximum ratio in resistance variation of MR was found to be 1.8%.

Ambri Mohamed, Mohd; Inami, Nobuhito; Shikoh, Eiji; Yamamoto, Yoshiyuki; Hori, Hidenobu; Fujiwara, Akihiko

2008-04-01

360

Acetylcholinesterase biosensor based on single-walled carbon nanotubes—Co phtalocyanine for organophosphorus pesticides detection  

Microsoft Academic Search

A simple and reliable technique has been developed for the construction of an amperometric acetylcholinesterase biosensor based on screen-printed carbon electrodes. For the first time, one-step modification using single-walled carbon nanotubes and Co phtalocyanine has been proposed to decrease the working potential and to increase the signal of thiocholine oxidation. The biosensor developed made it possible to detect 5–50ppb of

A. N. Ivanov; R. R. Younusov; G. A. Evtugyn; F. Arduini; D. Moscone; G. Palleschi

2011-01-01

361

Surface defect site density on single walled carbon nanotubes by titration  

Microsoft Academic Search

Closed end single walled carbon nanotubes (c-SWNT) purified by acidic oxidation have been studied in order to determine the fraction of oxidized carbon sites present. This has been done by measuring the evolution of CO2(g) and CO(g) on heating to 1273 K. Following a 1273 K treatment, the defect sites were titrated repeatedly with O3. The results indicate that ?5%

Douglas B. Mawhinney; Viktor Naumenko; Anya Kuznetsova; John T. Yates Jr; J. Liu; R. E. Smalley

2000-01-01

362

Covalent functionalization of single walled carbon nanotubes with peptide nucleic acid: Nanocomponents for molecular level electronics  

Microsoft Academic Search

Imparting molecular recognition to carbon nanotubes (CNTs) by conjugating them with bio-molecules has been an area of great interest as the resulting highly functionalized CNT-bioconjugates find their applications in various fields like molecular level electronics, pharmaceuticals, drug delivery, novel materials and many others. In this work we demonstrate the synthesis of functionally engineered single walled carbon nanotubes (SWNTs)-peptide nucleic acid

Krishna V. Singh; Rajeev R. Pandey; Xu Wang; Roger Lake; Cengiz S. Ozkan; Kang Wang; Mihrimah Ozkan

2006-01-01

363

Nano Surface Generation of Inconel 600 Material by Grinding Process using Single Wall Carbon Nanotubes  

Microsoft Academic Search

The mainstay of this work is to compare the surface roughness of Inconel600 material by grinding process using several samples of cutting fluid such as Mineral oil, SAE 20W40 oil and mixture of SAE 20W40 oil with Single Wall Carbon Nano Tube (SWCNT). Carbon nano tubes have been of great interest, both from a fundamental point of view and for

S. Prabhu; B. K. Vinayagam

364

Tailoring the diameter of single-walled carbon nanotubes for optical applications  

Microsoft Academic Search

Single-walled carbon nanotubes (SWCNTs) with specific diameters are required for various applications particularly in electronics\\u000a and photonics, since the diameter is an essential characteristic determining their electronic and optical properties. In this\\u000a work, the selective growth of SWCNTs with a certain mean diameter is achieved by the addition of appropriate amounts of CO2 mixed with the carbon source (CO) into

Ying Tian; Marina Y. Timmermans; Samuli Kivistö; Albert G. Nasibulin; Zhen Zhu; Hua Jiang; Oleg G. Okhotnikov; Esko I. Kauppinen

365

Fabrication of spintronics device by direct synthesis of single-walled carbon nanotubes from ferromagnetic electrodes  

Microsoft Academic Search

We describe an alternative method for realizing a carbon nanotube spin field-effect transistor device by the direct synthesis of single-walled carbon nanotubes (SWNTs) on substrates by alcohol catalytic chemical vapor deposition. We observed hysteretic magnetoresistance (MR) at low temperatures due to spin-dependent transport. In these devices, the maximum ratio in resistance variation of MR was found to be 1.8%.

Mohd Ambri Mohamed; Nobuhito Inami; Eiji Shikoh; Yoshiyuki Yamamoto; Hidenobu Hori; Akihiko Fujiwara

2008-01-01

366

Shape Engineerable Single Walled Carbon Nanotube Solid as a Flexible Conducting Mesoporous Material  

Microsoft Academic Search

We present a new form of carbon nanotubes (CNT) material where CNTs are aligned and packed densely in a bulk solid. This single-walled carbon nanotube (SWNT) solid is fabricated from liquid-induced collapse of the sparse as-grown SWNT forest synthesized by super-growth CVD [1], which results in a 20x increase in mass density and a 70x increase in the Vickers hardness

Don N. Futaba; Kenji Hata; Tatsuki Hiraoka; Takeo Yamada; Kohei Mizuno; Yuhei Hayamizu; Tatsunori Namai; Yozo Kakudate; Osamu Tanaike; Hiroaki Hatori; Koji Miyake; Shinya Sasaki; Motoo Yumura; Sumio Iijima

2006-01-01

367

Polypropylene \\/Single Wall Carbon Nano Tube Composites Crystallization Behavior and Fiber Processing Studies  

Microsoft Academic Search

Single Wall Carbon Nanotubes (SWNTs) produced using high-pressure carbon monoxide (HiPCO) process have been purified using the previously developed method to remove the catalytic impurities. Polypropylene (PP) with 1 wtmelt blended in a Haake mixer at 240oC. The resulting PP\\/SWNT blend was optically inhomogeneous. The polymer melt was filtered through a 300, 250, 120 and 80 mesh stainless steel filter

T. V. Sreekumar; Arup R. Bhattacharyya; Atul Kumar; Huina Guo; Satish Kumar; Lars Ericson; Richard E. Smalley

2002-01-01

368

Structure and Properties of poly (para phynelyne benzobisoxazole) (PBO) \\/single wall carbon nano tube composite fibers  

Microsoft Academic Search

The liquid crystalline compositions are prepared by the in-situ polycondensation of diamines and diacid monomers in the presence of single wall carbon nano tubes (SWNT). Processing of the new compositions into fibers provide hybrid materials with improved mechanical properties. The in-situ polymerizations were carried out in polyphosphoric acid (PPA). Carbon nano tubes as high as 10 wt.polymer weight have been

Satish Kumar; Xiefei Zhang; Arup R. Bhattacharyya; Byung G. Min; T. D. Dang; F. E. Arnold; Richard A. Vaia; S. Ramesh; P. A. Willis; R. H. Hauge; R. E. Smalley

2002-01-01

369

Role of catalysts in the surface synthesis of single-walled carbon nanotubes  

Microsoft Academic Search

We demonstrate the role of catalysts in the surface growth of single-walled carbon nanotubes (SWNTs) by reviewing recent progress\\u000a in the surface synthesis of SWNTs. Three effects of catalysts on surface synthesis are studied: type of catalyst, the relationship\\u000a between the size of catalyst particles and carbon feeding rates, and interactions between catalysts and substrates. Understanding\\u000a of the role of

Weiwei Zhou; Lei Ding; Jie Liu

2009-01-01

370

Nerve agent detection using networks of single-walled carbon nanotubes  

Microsoft Academic Search

We report the use of carbon nanotubes as a sensor for chemical nerve agents. Thin-film transistors constructed from random networks of single-walled carbon nanotubes were used to detect dimethyl methylphosphonate (DMMP), a simulant for the nerve agent sarin. These sensors are reversible and capable of detecting DMMP at sub-ppb concentration levels, and they are intrinsically selective against interferent signals from

J. P. Novak; E. S. Snow; E. J. Houser; J. L. Stepnowski; R. A. McGill

2003-01-01

371

The Production of Single-Wall Carbon Nanotubes with Specific Diameters by Controlling Pulsed Laser Vaporization Synthesis Parameters  

Microsoft Academic Search

Carbon single-wall nanotubes (SWNTs) may be employed in a variety of applications including the fabrication of nanoscale wires and interconnects, gas storage and separation systems and strong composite materials. Because the properties of SWNTs vary with their size and structure, it is necessary to obtain greater control over the synthesis of specific types of carbon nanotubes. The production of single-walled

Anne Dillon

2001-01-01

372

DOE Hydrogen Sorption Center of Excellence: Synthesis and Processing of Single-Walled Carbon Nanohorns for Hydrogen Storage and Catalyst Supports  

Microsoft Academic Search

The objective of the project was to exploit the unique morphology, tunable porosity and excellent metal supportability of single-walled carbon nanohorns (SWNHs) to optimize hydrogen uptake and binding energy through an understanding of metal-carbon interactions and nanoscale confinement. SWNHs provided a unique material to understand these effects because they are carbon nanomaterials which are synthesized from the 'bottom-up' with well-defined,

David B. Geohegan; Hui Hu; Mina Yoon; Alex A. Puretzky; Christopher M. Rouleau; Norbert Thonnard; Gerd Duscher; Karren More

2011-01-01

373

Effect of Different Carbon Sources on the Growth of Single-Walled Carbon Nanotube from MCM-41 Containing Nickel  

SciTech Connect

Chemical vapor deposition growth of single-walled carbon nanotubes (SWCNTs) was studied using three representative carbon source sources: CO, ethanol, and methane, and a catalyst of Ni ions incorporated in MCM-41. The resulting SWCNTs were compared for similar reaction conditions. Carbon deposits were analyzed by multi-excitation wavelength Raman, TGA, TEM and AFM. Catalytic particles in the Ni-MCM-41 catalysts were characterized by TEM and synchrotron light source X-ray absorption spectroscopy. Under similar synthesis conditions, SWCNTs produced from CO had a relatively smaller diameter, while those from ethanol had a larger diameter. Methane could not produce SWCNTs on Ni-MCM-41 under the conditions used in this research. These results demonstrate that three carbon sources affect the dynamic balances between metallic cluster formation and carbon deposition/precipitation on the metallic cluster surface. Controlling SWCNT diameter relies on precisely regulating this dynamic process. Using different carbon sources we are able to shift this dynamic balance and produce SWCNTs with different mean diameters.

Chen,Y.; Wang, B.; Li, L.; Yang, Y.; Ciuparu, D.; Lim, S.; Haller, G.; Pfefferle, L.

2007-01-01

374

Peptide secondary structure modulates single-walled carbon nanotube fluorescence as a chaperone sensor for nitroaromatics  

PubMed Central

A class of peptides from the bombolitin family, not previously identified for nitroaromatic recognition, allows near-infrared fluorescent single-walled carbon nanotubes to transduce specific changes in their conformation. In response to the binding of specific nitroaromatic species, such peptide–nanotube complexes form a virtual “chaperone sensor,” which reports modulation of the peptide secondary structure via changes in single-walled carbon nanotubes, near-infrared photoluminescence. A split-channel microscope constructed to image quantized spectral wavelength shifts in real time, in response to nitroaromatic adsorption, results in the first single-nanotube imaging of solvatochromic events. The described indirect detection mechanism, as well as an additional exciton quenching-based optical nitroaromatic detection method, illustrate that functionalization of the carbon nanotube surface can result in completely unique sites for recognition, resolvable at the single-molecule level.

Heller, Daniel A.; Pratt, George W.; Zhang, Jingqing; Nair, Nitish; Hansborough, Adam J.; Boghossian, Ardemis A.; Reuel, Nigel F.; Barone, Paul W.; Strano, Michael S.

2011-01-01

375

Electronic-structure-dependent bacterial cytotoxicity of single-walled carbon nanotubes.  

PubMed

Single-walled carbon nanotubes (SWNTs) have been previously observed to be strong antimicrobial agents, and SWNT coatings can significantly reduce biofilm formation. However, the SWNT antimicrobial mechanism is not fully understood. Previous studies on SWNT cytotoxicity have concluded that membrane stress (i.e., direct SWNT-bacteria contact resulting in membrane perturbation and the release of intracellular contents) was the primary cause of cell death. Gene expression studies have indicated oxidative stress may be active, as well. Here, it is demonstrated for the first time how SWNT electronic structure (i.e., metallic versus semiconducting) is a key factor regulating SWNT antimicrobial activity. Experiments were performed with well-characterized SWNTs of similar length and diameter but varying fraction of metallic nanotubes. Loss of Escherichia coli viability was observed to increase with an increasing fraction of metallic SWNTs. Time-dependent cytotoxicity measurements indicated that in all cases the majority of the SWNT antimicrobial action occurs shortly after (<15 min) bacteria-SWNT contact. The SWNT toxicity mechanism was investigated by in vitro SWNT-mediated oxidation of glutathione, a common intracellular thiol that serves as an antioxidant and redox state mediator. The extent of glutathione oxidation was observed to increase with increasing fraction of metallic SWNTs, indicating an elevated role of oxidative stress. Scanning electron microscopy images of E. coli in contact with the SWNTs demonstrated electronic structure-dependent morphological changes consistent with cytotoxicity and glutathione oxidation results. A three-step SWNT antimicrobial mechanism is proposed involving (i) initial SWNT-bacteria contact, (ii) perturbation of the cell membrane, and (iii) electronic structure-dependent bacterial oxidation. PMID:20812689

Vecitis, Chad D; Zodrow, Katherine R; Kang, Seoktae; Elimelech, Menachem

2010-09-28

376

Sorted and aligned single-walled carbon nanotube networks for transistor-based aqueous chemical sensors.  

PubMed

Detecting trace amounts of analytes in aqueous systems is important for health diagnostics, environmental monitoring, and national security applications. Single-walled carbon nanotubes (SWNTs) are ideal components for both the sensor material and active signal transduction layer because of their excellent electronic properties and high aspect ratio consisting of entirely surface atoms. Submonolayer arrays, or networks of SWNTs (SWNTnts) are advantageous, and we show that topology characteristics of the SWNT network, such as alignment, degree of bundling, and chirality enrichment strongly affect the sensor performance. To enable this, thin-film transistor (TFT) sensors with SWNTnts were deposited using a one-step, low-cost, solution- based method on a polymer dielectric, allowing us to achieve stable low-voltage operation under aqueous conditions. These SWNT-TFTs were used to detect trace concentrations, down to 2 ppb, of dimethyl methylphosphonate (DMMP) and trinitrotoluene (TNT) in aqueous solutions. Along with reliable cycling underwater, the TFT sensors fabricated with aligned, sorted nanotube networks (enriched with semiconductor SWNTs) showed a higher sensitivity to analytes than those fabricated with random, unsorted networks with predominantly metallic charge transport. PMID:19856982

Roberts, Mark E; LeMieux, Melburne C; Bao, Zhenan

2009-10-27

377

Flexible single-walled carbon nanotube/polycellulose papers for lithium-ion batteries.  

PubMed

Flexible and highly conductive single-walled carbon nanotube/polycellulose papers (SWCNT/PPs) were developed as current collectors for lithium-ion batteries by a simple and scalable process. The flexible electrodes based on SWCNT/PP conductors consisted of a unique three-dimensional interwoven structure of electrode materials and cellulose fibers with CNTs and exhibited flexibility, good electrochemical performance and excellent cyclic stability. Full cells using Li(4)Ti(5)O(12) and LiFePO(4) electrodes based on SWCNT/PPs showed a first discharge capacity of 153.5 mA h g(-1) with Coulombic efficiencies of 90.6% at 0.1 C and discharge capacity of 102.6 mA h g(-1) at high rate (10 C). Full cells based SWCNT/PP conductors showed higher capacities and lower electrochemical interfacial resistance compared to metallic current collectors. Half cells using anatase TiO(2) hierarchical spheres based on SWCNT/PP conductors also exhibited outstanding electrochemical performance, verifying the stability of SWCNT/PP conductors to various electrode materials. Our results demonstrated the potential versatility of composite electrodes and conductive SWCNT/PPs for flexible and portable micropower devices. PMID:23150071

Wang, Jin; Li, Linlin; Wong, Chui Ling; Madhavi, Srinivasan

2012-11-13

378

Two photon polymerization lithography for 3D microfabrication of single wall carbon nanotube/polymer composites  

NASA Astrophysics Data System (ADS)

Two photon polymerization (TPP) lithography has been established as a powerful tool to develop 3D fine structures of polymer materials, opening up a wide range applications such as micro-electromechanical systems (MEMS). TPP lithography is also promising for 3D micro fabrication of nanocomposites embedded with nanomaterials such as metal nanoparticles. Here, we make use of TPP lithography to fabricate 3D micro structural single wall carbon nanotube (SWCNT)/polymer composites. SWCNTs exhibit remarkable mechanical, electrical, thermal and optical properties, which leads to enhance performances of polymers by loading SWCNTs. SWCNTs were uniformly dispersed in an acrylate UV-curable monomer including a few amounts of photo-initiator and photo-sensitizer. A femtosecond pulsed laser emitting at 780 nm was focused onto the resin, resulting in the photo-polymerization of a nanometric volume of the resin through TPP. By scanning the focus spot three dimensionally, arbitrary 3D structures were created. The spatial resolution of the fabrication was sub-micrometer, and SWCNTs were embedded in the sub-micro sized structures. The fabrication technique enables one to fabricate 3D micro structural SWCNT/polymer composites into desired shapes, and thus the technique should open up the further applications of SWCNT/polymer composites such as micro sized photomechanical actuators.

Ushiba, Shota; Shoji, Satoru; Kuray, Preeya; Masui, Kyoko; Kono, Junichiro; Kawata, Satoshi

2013-03-01

379

Block copolymer assisted dispersion of single walled carbon nanotubes and integration into a trifunctional epoxy.  

PubMed

Arc discharge single walled carbon nanotubes were processed by acid treatment, dispersion in a Pluronic F68 block copolymer aqueous solution and centrifugation. The as-prepared material was characterized by transmission electron microscopy, X-ray diffraction and Raman spectroscopy, showing an important degree of debundling as well as the removal of most of the graphitic and metallic impurities from pristine nanotubes. The nanotube-Pluronic material was integrated into an advanced trifunctional epoxy resin, triglycidyl p-aminophenol, using 4,4'-diaminodiphenylsulfone as the curing agent. The material was incorporated into the epoxy system (0.1, 0.25, 0.50, 1.0, 2.0 wt%) throughout hot magnetic stirring and ultrasonication. Curing kinetics was studied using differential scanning calorimetry, applying the Vyazovkin's isoconversional method. In the early stages of curing, the kinetic study revealed a decrease in the activation energy for samples containing Pluronic, suggesting that Pluronic induced an improvement in the mobility of reactants. The cured composites were characterized by Raman spectroscopy, thermogravimetric analysis and scanning electron microscopy. Micrographs revealed successful integration and homogeneous distribution of the nanotube-Pluronic material in the epoxy matrix, while direct integration of bare nanotubes originated aggregates and inhomogeneity. PMID:19908501

González-Domínguez, J M; Castell, P; Ansón, A; Maser, W K; Benito, A M; Martinez, M T

2009-10-01

380

Comparison of analytical techniques for purity evaluation of single-walled carbon nanotubes.  

PubMed

We compare popular analytical techniques, including scanning and transmission electron microscopy (SEM and TEM), thermogravimetric analysis (TGA), and Raman and near-infrared (NIR) spectroscopy, for the evaluation of the purity of bulk quantities of single-walled carbon nanotubes (SWNTs). Despite their importance as imaging techniques, SEM and TEM are not capable of quantitatively evaluating the purity of typical inhomogeneous bulk SWNT samples because the image frame visualizes less than 1 pg of SWNT material; furthermore, there is no published algorithm to convert such images into numerical data. The TGA technique is capable of measuring the amount of metal catalyst in an SWNT sample, but does not provide an unambiguous separation between the content of SWNTs and carbonaceous impurities. We discuss the utilization of solution-phase near-infrared spectroscopy and solution-phase Raman spectroscopy to quantitatively compare arbitrary samples of bulk SWNT materials of different purities. The primary goal of this paper is to provide the chemical community with a realistic evaluation of current analytical tools for the purity evaluation of a bulk sample of SWNTs. The secondary goal is to draw attention to the growing crisis in the SWNT industry as a result of the lack of quality control and the misleading advertising by suppliers of this material. PMID:15755163

Itkis, Mikhail E; Perea, Daniel E; Jung, Richard; Niyogi, Sandip; Haddon, Robert C

2005-03-16

381

Flexible single-walled carbon nanotube/polycellulose papers for lithium-ion batteries  

NASA Astrophysics Data System (ADS)

Flexible and highly conductive single-walled carbon nanotube/polycellulose papers (SWCNT/PPs) were developed as current collectors for lithium-ion batteries by a simple and scalable process. The flexible electrodes based on SWCNT/PP conductors consisted of a unique three-dimensional interwoven structure of electrode materials and cellulose fibers with CNTs and exhibited flexibility, good electrochemical performance and excellent cyclic stability. Full cells using Li4Ti5O12 and LiFePO4 electrodes based on SWCNT/PPs showed a first discharge capacity of 153.5 mA h g-1 with Coulombic efficiencies of 90.6% at 0.1 C and discharge capacity of 102.6 mA h g-1 at high rate (10 C). Full cells based SWCNT/PP conductors showed higher capacities and lower electrochemical interfacial resistance compared to metallic current collectors. Half cells using anatase TiO2 hierarchical spheres based on SWCNT/PP conductors also exhibited outstanding electrochemical performance, verifying the stability of SWCNT/PP conductors to various electrode materials. Our results demonstrated the potential versatility of composite electrodes and conductive SWCNT/PPs for flexible and portable micropower devices.

Wang, Jin; Li, Linlin; Wong, Chui Ling; Madhavi, Srinivasan

2012-12-01

382

Noncovalent interactions between organometallic metallocene complexes and single-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

First principles density functional pseudopotential calculations have been used to investigate the nature of interactions between single-walled carbon nanotubes (SWNTs) and intercalated transition metal metallocene complexes, M(?-C5H5)2 (MCp2). Three composites, MCp2-graphene (dt=?), MCp2@(17,0) (dt=1.33 nm), and MCp2@(12,0) (dt=0.94 nm) (where M=Fe,Co), have been studied to probe the influence of the nanotube diameter (dt) on the nature and magnitude of the interactions. Theoretical results presented here demonstrate that these MCp2@SWNT composites are stabilized by weak ?-stacking and CH...? interactions, and in the case of the CoCp2@SWNT composites there is an additional electrostatic contribution as a result of charge transfer from CoCp2 to the nanotube. The extent of charge transfer (MCp2-->SWNT) can be rationalized in terms of the electronic structures of the two fragments, or more specifically, the relative positions of the metallocene highest occupied molecular orbital and the conduction band of the nanotube in the electronic structure of the composite.

Sceats, Emma L.; Green, Jennifer C.

2006-10-01

383

Raman Spectroscopy of Charge Transfer Interactions Between Single Wall Carbon Nanotubes and [FeFe] Hydrogenase  

SciTech Connect

We report a Raman spectroscopy study of charge transfer interactions in complexes formed by single-walled carbon nanotubes (SWNTs) and [FeFe] hydrogenase I (CaHydI) from Clostridium acetobutylicum. The choice of Raman excitation wavelength and sample preparation conditions allows differences to be observed for complexes involving metallic (m) and semiconducting (s) species. Adsorbed CaHydI can reversibly inject electronic charge into the LUMOs of s-SWNTs, while charge can be injected and removed from m-SWNTs at lower potentials just above the Fermi energy. Time-dependent enzymatic assays demonstrated that the reduced and oxidized forms of CaHydI are deactivated by oxygen, but at rates that varied by an order of magnitude. The time evolution of the oxidative decay of the CaHydI activity reveals different time constants when complexed with m-SWNTs and s-SWNTs. The correlation of enzymatic assays with time-dependent Raman spectroscopy provides a novel method by which the charge transfer interactions may be investigated in the various SWNT-CaHydI complexes. Surprisingly, an oxidized form of CaHydI is apparently more resistant to oxygen deactivation when complexed to m-SWNTs rather than s-SWNTs.

Blackburn, J. L. Svedruzic, D.; McDonald, T. J.; Kim, Y. H.; King, P. W.; Heben, M. J.

2008-01-01

384

Electro-oxidation of hydrazine at gold nanoparticle functionalised single walled carbon nanotube network ultramicroelectrodes.  

PubMed

Networks of pristine single walled carbon nanotubes (SWNTs) grown by catalysed chemical vapour deposition (cCVD) on an insulating surface and arranged in an ultramicroelectrode (UME) format are insensitive to the electro-oxidation of hydrazine (HZ) in aqueous solution, indicating a negligible metallic nanoparticle content. Sensitisation of the network towards HZ oxidation is promoted by the deliberate and controlled electrodeposition of "naked" gold (Au) nanoparticles (NPs). By controlling the deposition conditions (potential, time) it is possible to control the size and spacing of the Au NPs on the underlying SWNT network. Two different cases are considered: Au NPs at a number density of 250 ± 13 NPs ?m(-2) and height 24 nm ± 5 (effective surface coverage, ? = 92%) and (ii) Au NPs of number density ~ 22 ± 3 NPs ?m(-2) and height 43 nm ± 8 nm (? = 35%). For both morphologies the HZ oxidation half-wave potential (E(1/2)) is shifted significantly negative by ca. 200 mV, compared to a gold disc UME of the same geometric area, indicating significantly more facile electron transfer kinetics. E(1/2) for HZ oxidation for the higher density Au NP-SWNT structure is shifted slightly more negative (by ~25 mV) than E(1/2) for the lower density Au NP electrode. This is attributed to the lower flux of HZ at NPs in the higher number density arrangement (smaller kinetic demand). Importantly, using this approach, the calculated HZ oxidation current density sensitivities for the Au NP-SWNT electrodes reported here are higher than for many other metal NP functionalised carbon nanotube electrodes. PMID:21869974

Dudin, Petr V; Unwin, Patrick R; Macpherson, Julie V

2011-08-25

385

Porphyrins-Functionalized Single-Walled Carbon Nanotubes Chemiresistive Sensor Arrays for VOCs.  

PubMed

Single-walled carbon nanotubes (SWNTs) have been used extensively for sensor fabrication due to its high surface to volume ratio, nanosized structure and interesting electronic property. Lack of selectivity is a major limitation for SWNTs-based sensors. However, surface modification of SWNTs with a suitable molecular recognition system can enhance the sensitivity. On the other hand, porphyrins have been widely investigated as functional materials for chemical sensor fabrication due to their several unique and interesting physico-chemical properties. Structural differences between free-base and metal substituted porphyrins make them suitable for improving selectivity of sensors. However, their poor conductivity is an impediment in fabrication of prophyrin-based chemiresistor sensors. The present attempt is to resolve these issues by combining freebase- and metallo-porphyrins with SWNTs to fabricate SWNTs-porphyrin hybrid chemiresistor sensor arrays for monitoring volatile organic carbons (VOCs) in air. Differences in sensing performance were noticed for porphyrin with different functional group and with different central metal atom. The mechanistic study for acetone sensing was done using field-effect transistor (FET) measurements and revealed that the sensing mechanism of ruthenium octaethyl porphyrin hybrid device was governed by electrostatic gating effect, whereas iron tetraphenyl porphyrin hybrid device was governed by electrostatic gating and Schottky barrier modulation in combination. Further, the recorded electronic responses for all hybrid sensors were analyzed using a pattern-recognition analysis tool. The pattern-recognition analysis confirmed a definite pattern in response for different hybrid material and could efficiently differentiate analytes from one another. This discriminating capability of the hybrid nanosensor devices open up the possibilities for further development of highly dense nanosensor array with suitable porphyrin for E-nose application. PMID:22393460

Shirsat, Mahendra D; Sarkar, Tapan; Kakoullis, James; Myung, Nosang V; Konnanath, Bharatan; Spanias, Andreas; Mulchandani, Ashok

2012-09-01

386

Porphyrins-Functionalized Single-Walled Carbon Nanotubes Chemiresistive Sensor Arrays for VOCs  

PubMed Central

Single-walled carbon nanotubes (SWNTs) have been used extensively for sensor fabrication due to its high surface to volume ratio, nanosized structure and interesting electronic property. Lack of selectivity is a major limitation for SWNTs-based sensors. However, surface modification of SWNTs with a suitable molecular recognition system can enhance the sensitivity. On the other hand, porphyrins have been widely investigated as functional materials for chemical sensor fabrication due to their several unique and interesting physico-chemical properties. Structural differences between free-base and metal substituted porphyrins make them suitable for improving selectivity of sensors. However, their poor conductivity is an impediment in fabrication of prophyrin-based chemiresistor sensors. The present attempt is to resolve these issues by combining freebase- and metallo-porphyrins with SWNTs to fabricate SWNTs-porphyrin hybrid chemiresistor sensor arrays for monitoring volatile organic carbons (VOCs) in air. Differences in sensing performance were noticed for porphyrin with different functional group and with different central metal atom. The mechanistic study for acetone sensing was done using field-effect transistor (FET) measurements and revealed that the sensing mechanism of ruthenium octaethyl porphyrin hybrid device was governed by electrostatic gating effect, whereas iron tetraphenyl porphyrin hybrid device was governed by electrostatic gating and Schottky barrier modulation in combination. Further, the recorded electronic responses for all hybrid sensors were analyzed using a pattern-recognition analysis tool. The pattern-recognition analysis confirmed a definite pattern in response for different hybrid material and could efficiently differentiate analytes from one another. This discriminating capability of the hybrid nanosensor devices open up the possibilities for further development of highly dense nanosensor array with suitable porphyrin for E-nose application.

Shirsat, Mahendra D.; Sarkar, Tapan; Kakoullis, James; Myung, Nosang V.; Konnanath, Bharatan; Spanias, Andreas; Mulchandani, Ashok

2012-01-01

387

Absolute potential of the Fermi level of single-walled carbon nanotubes via hydrogenase complex formation.  

NASA Astrophysics Data System (ADS)

The absolute potential of the Fermi level of nanotubes as a function of nanotube type is not presently understood, and is important for many nanotube applications and sorting strategies. Here, we study complexes of recombinant [FeFe] hydrogenases and single-walled carbon nanotubes. We find evidence that novel charge-transfer complexes are formed and are stable, which enables further study and application of this system. The hydrogenase functions as a hydrogen electrode sensitizing the nanotubes to the redox half-reaction for hydrogen. Thus the potential can be altered by changing the molecular hydrogen concentration, and this tunability is utilized to bleach various semiconducting nanotube transitions. By observing which are bleached and which remain emissive, we determine the alignment of the potential of the Fermi level of semiconducting single-walled carbon nanotubes. The experimentally determined Fermi level alignment is confirmed theoretically by the first-principles DFT-PBE method.

McDonald, Timothy; Svedruzic, Drazenka; Kim, Yong-Hyun; Blackburn, Jeffrey; Zhang, Shengbai; King, Paul; Heben, Michael

2007-03-01

388

Molecular dynamics simulation studies of structural and mechanical properties of single-walled carbon nanotubes.  

PubMed

Structural and mechanical properties of armchair, zig-zag and chiral single-walled carbon nanotubes are computed by employing Molecular Dynamics simulation technique using Discover code with Compass force field via Materials Studio program developed by the Accelrys. Consistent with the literature, we find that the armchair SWCNT is energetically favored over zig-zag and chiral nanotubes. Predicted structural parameters agree well with experimental observations. Observed radial distribution functions show that the single-walled carbon nanotubes remain crystalline after exposing them to 300 K. The predicted Young's and the Shear moduli were in reasonable agreement with other reports. Our predictions show that the Young's modulus of the tubes increases as the diameter of the tube decreases. PMID:21121299

Mashapa, Matete G; Ray, Suprakas Sinha

2010-12-01

389

Paper transistor made with regenerated cellulose and covalently bonded single-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

We report a flexible paper transistor made with regenerated cellulose and covalently bonded single-walled carbon nanotubes. Functionalized single-walled carbon nanotubes (SWNTs) are reacted with N, N-Carbonyldiimidazoles to obtain SWNTs-imidazolides. SWNTs can be covalently bonded to cellulose by acylation of cellulose with SWNTsimidazolides. Using the product, SWNTs covalently bonded cellulose (S/C) composite paper is fabricated and it is mechanically stretched to align SWNTs with cellulose chains. Finally, inter-digital comb shaped source and drain electrode and bottom gate electrode is formed on the paper via lift-off process. Aligned SWNTs can contribute to establishing stable electron channel paths in the cellulose layer. The alignment of SWNTs can be key a role in improving characteristics of the paper transistor. The characteristics of the paper transistor are evaluated by measuring mobility, onoff ratio depending on the alignment of SWNTs in S/C composite paper transistors.

Yun, Sungryul; Ko, Hyun-U.; Kim, Joo-Hyung; Lim, Byung-Wook; Kim, Jaehwan

2011-03-01

390

Photoreactivity of carboxylated single-walled carbon nanotubes in sunlight: reactive oxygen species production in water.  

PubMed

Very limited information exists on transformation processes of carbon nanotubes in the natural aquatic environment. Because the conjugated pi-bond structure of these materials is efficient in absorbing sunlight, photochemical transformations are a potential fate process with reactivity predicted to vary with their diameter, chirality, number and type of defects, functionalization, residual metal catalyst and amorphous carbon content, and with the composition of the water, including the type and composition of materials that act to disperse them into the aqueous environment. In this study, the photochemical reactions involving colloidal dispersions of carboxylated single-walled carbon nanotubes (SWNT-COOH) in sunlight were examined. Production of reactive oxygen species (ROS) during irradiation occurs and is evidence for potential further phototransformation and may be significant in assessing their overall environmental impacts. In aerated samples exposed to sunlight or to lamps that emit light only within the solar spectrum, the probe compounds, furfuryl alcohol (FFA), tetrazolium salts (NBT2+ and XTT), and p-chlorobenzoic acid (pCBA), were used to indicate production of 1O2, O2.-, and .OH, respectively. All three ROS were produced in the presence of SWNT-COOH and molecular oxygen (3O2). 1O2 production was confirmed by observing enhanced FFA decay in deuterium oxide, attenuated decay of FFA in the presence of azide ion, and the lack of decay of FFA in deoxygenated solutions. Photogeneration of O2.- and .OH was confirmed by applying superoxide dismutase (SOD) and tert-butanol assays, respectively. In air-equilibrated suspensions, the loss of 0.2 mM FFA in 10 mg/L SWNT-COOH was approximately 85% after 74 h. Production of 1O2 was not dependent on pH from 7 to 11; however photoinduced aggregation was observed at pH 3. PMID:20687543

Chen, Chia-Ying; Jafvert, Chad T

2010-09-01

391

Density Functional Studies of the 13C NMR Chemical Shifts in Single-Walled Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

Density functional theory has been used to compute the electronic structure and 13C NMR chemical shifts of finite (9,0) single-walled carbon nanotubes (SWNTs) capped with fullerene hemispheres and with hydrogen atoms. The chemical shifts and HOMO-LUMO gaps were found to be dependent upon the mode of capping. The shifts of semiconducting and metallic tubes were estimated as being around 130 ppm and 141 ppm, respectively. Periodic boundary calculations on infinite zigzag (n,0) SWNTs with 7<=n<=17 were performed. These entities can be characterized by a family index, ? = mod(n,3), and the chemical shifts can be fitted well by a function inversely proportional to the diameter of the tube and proportional to a constant which depends on the nanotube family. Direct comparison of the molecular and periodic approaches can be made if benzene is used as the internal reference. Such a comparison indicates that capping may have a strong effect on the computed properties. Calculations on infinite zigzag (7<=n<=10) amine functionalized SWNTs have been performed. The functional group may react with a C-C bond which is parallel or diagonal to the tube axis and both sites have been considered. The shifts of the carbons directly attached to the group are sensitive to the bond which has been functionalized and may therefore be used to discriminate between the two products. Functionalization induces a significant line broadening of the NMR signals but it does not dramatically change the average shift of the unfunctionalized SWNT carbons.

Zurek, Eva; Autschbach, Jochen

2007-12-01

392

Single-walled carbon nanotubes synthesis: a direct comparison of laser ablation and carbon arc routes.  

PubMed

Carbon arc and chemical vapor deposition are at present the most efficient methods for mass production of single-walled carbon nanotubes. However, laser ablation is renowned for high quality nanotubes with narrow diameter distributions and hence is also of great interest. The aim of this work was to compare both the carbon arc and laser ablation techniques with respect to the quality--and relative yield of the produced SWCNTs. For this comparative study we used Fe as the catalyst, which is known not to be very active in laser ablation. However, we show this is not the case when H2 is included in the reaction. The reactions for both synthesis routes were carried out in a N2-H2 (95-5% vol.) atmosphere. The same homogenous carbon rods with different iron contents, between 1 and 5 at.% were used as the carbon feedstock and catalyst supply in both synthesis routes. Additionally, two types of carbon rods containing 1 at.% Fe with different graphitization degrees were also investigated. In the arc-discharge case, the low-graphitized electrode produced a web-like product rich in SWCNTs, while the high-graphitized carbon rods yielded soot containing carbon-encapsulated iron nanocrystallites, amorphous carbon nanoparticles, and surprisingly a small fraction of SWCNTs. With laser ablation synthesis, the Fe content and the reactor temperature significantly influenced the SWCNTs yield. Carbon arc plasma diagnostics were also performed. By using optical emission and Absorption spectroscopy the plasma temperature, C2 and CN radical content in the arc zone were determined. PMID:19198361

Bystrzejewski, M; Rümmeli, M H; Lange, H; Huczko, A; Baranowski, P; Gemming, T; Pichler, T

2008-11-01

393

Influence of nanoparticle size to the electrical properties of naphthalenediimide on single-walled carbon nanotube wiring  

NASA Astrophysics Data System (ADS)

Nanoparticles of N,N?-bis(n-alkyl)tetracarbonatenaphthalenediimide (NDI) were adsorbed on single-walled carbon nanotube (SWNT) wires dispersed on a SiO2 substrate. The electrical properties were measured along the long axis of the SWNTs, and in all cases through the nanoparticles showed rectification in semiconducting I-V curve. The plateau width of the I-V curve through the NDI nanoparticles on metallic SWNTs decreased as the particle size increased, while the rectification ratio increased. The conduction mechanism was changed from tunneling conduction to Schottky-like conduction and their boundary is at about 3 nm diameter.

Tanaka, Hirofumi; Hong, Liu; Fukumori, Minoru; Negishi, Ryota; Kobayashi, Yoshihiro; Tanaka, Daisuke; Ogawa, Takuji

2012-06-01

394

Ion Beam Bombardment Effect on Contacts in Solution-Processed Single-Walled Carbon Nanotube Thin Film Transistor  

NASA Astrophysics Data System (ADS)

Effect of argon ion bombardment (AIB) on performance of solution-processed single-walled carbon nanotube (SWCNT) thin film transistor (TFT) has been investigated. AIB was applied to the source/drain contacts to reduce contact resistance. It was found that AIB enhances on-state current of TFT. Over 5 decades' on/off ratio is obtained by applying AIB. Results of transmission line method using metallic SWCNT clearly indicate that contact resistance between CNT network and Au electrode is reduced by the application of AIB.

Yi, Xun; Nakagawa, Gou; Ozawa, Hiroaki; Fujigaya, Tsuyohiko; Nakashima, Naotoshi; Asano, Tanemasa

2011-09-01

395

Molecular simulation of hydrogen adsorption in single-walled carbon nanotubes and idealized carbon slit pores  

NASA Astrophysics Data System (ADS)

The adsorption of hydrogen gas into single-walled carbon nanotubes (SWNTs) and idealized carbon slit pores is studied by computer simulation. Hydrogen-hydrogen interactions are modeled with the Silvera-Goldman potential. The Crowell-Brown potential is used to model the hydrogen-carbon interactions. Calculations include adsorption inside the tubes, in the interstitial regions of tube arrays, and on the outside surface of isolated tubes. Quantum effects are included through implementation of the path integral formalism. Comparison with classical simulations gives an indication of the importance of quantum effects for hydrogen adsorption. Quantum effects are important even at 298 K for adsorption in tube interstices. We compare our simulations with experimental data for SWNTs, graphitic nanofibers, and activated carbon. Adsorption isotherms from simulations are in reasonable agreement with experimental data for activated carbon, but do not confirm the large uptake reported for SWNTs and nanofibers. Although the adsorption potential for hydrogen in SWNTs is enhanced relative to slit pores of the same size, our calculations show that the storage capacity of an array of tubes is less than that for idealized slit pore geometries, except at very low pressures. Ambient temperature isotherms indicate that an array of nanotubes is not a suitable sorbent material for achieving DOE targets for vehicular hydrogen storage.

Wang, Qinyu; Johnson, J. Karl

1999-01-01

396

Random networks and aligned arrays of single-walled carbon nanotubes for electronic device applications  

Microsoft Academic Search

Singled-walled carbon nanotubes (SWNTs), in the form of ultrathin films of random networks, aligned arrays, or anything in\\u000a between, provide an unusual type of electronic material that can be integrated into circuits in a conventional, scalable fashion.\\u000a The electrical, mechanical, and optical properties of such films can, in certain cases, approach the remarkable characteristics\\u000a of the individual SWNTs, thereby making

Qing Cao; John A. Rogers

2008-01-01

397

Coherent injection and control of ballistic charge currents in single-walled carbon nanotubes and graphite  

Microsoft Academic Search

We report results from a comprehensive set of experiments to study coherently controlled electrical current injection in single-walled carbon nanotubes (SWNTs) and graphite. Photocurrents were injected at room temperature through the quantum interference of single- and two-photon absorption pathways induced by 150-fs optical pulses with 660-980 and 1320-1960-nm central wavelengths, respectively, and with maximum intensities of 10 and 0.15 GW

R. W. Newson; A. A. Green; M. C. Hersam; H. M. van Driel

2011-01-01

398

Thermal conductivity and interfacial resistance in single-wall carbon nanotube epoxy composites  

Microsoft Academic Search

We report thermal conductivity measurements of purified single-wall carbon nanotube (SWNT) epoxy composites prepared using suspensions of SWNTs in N-N-Dimethylformamide (DMF) and surfactant stabilized aqueous SWNT suspensions. Thermal conductivity enhancement is observed in both types of composites. DMF-processed composites show an advantage at SWNT volume fractions between phi~0.001 to 0.005. Surfactant processed samples, however, permit greater SWNT loading and exhibit

M. B. Bryning; D. E. Milkie; M. F. Islam; J. M. Kikkawa; A. G. Yodh

2005-01-01

399

Preferential Growth of Semiconducting Single-Walled Carbon Nanotubes on Substrate by Europium Oxide  

Microsoft Academic Search

In this paper, we have demonstrated that europium oxide (Eu2O3) is a new type of active catalyst for single-walled carbon nanotubes (SWNTs) growth under suitable conditions. Both random\\u000a SWNT networks and horizontally aligned SWNT arrays are efficiently grown on silicon wafers. The density of the SWNT arrays\\u000a can be altered by the CVD conditions. This result further provides the experimental

Yong QianBin; Bin Huang; Fenglei Gao; Chunyan Wang; Guangyuan Ren

2010-01-01

400

Ultrafast Terahertz Probes of Individualized, Chirality-Enriched Single-Walled Carbon Nanotubes  

Microsoft Academic Search

Singled-walled carbon nanotubes (SWNTs) represent a model system to systematically investigate correlated charge excitation in 1-D limits. One of the most outstanding issues both in fundamental nanotube physics and for their technological development is to detect and understand optically-forbidden, dark collective states. Thus far supporting evidence of dark states has been demonstrated in static magneto-optics and light scattering. However, the

Liang Luo; Ioannis Chatzakis; Jigang Wang

2011-01-01

401

Collisions of deuterium and tritium atoms with single-wall carbon nanotube: adsorption, encapsulation, and healing  

Microsoft Academic Search

Molecular dynamics simulations (MDSs) are used to study the collisions of deuterium (D) and tritium (T) atoms with single-wall carbon nanotube (SWNT) in the incident energy range of 1–33 eV. The MDSs show the scattering, encapsulation of deuterium and tritium, and the formation of exohedral D-SWNT, T-SWNT complexes. The hole on the sidewall induced by energetic atoms can be healed in

Yuchen Ma; Yueyuan Xia; Mingwen Zhao; M. Ying; Xiangdong Liu; Pijun Liu

2001-01-01

402

Study on Cluster Formation of Poly 2-HYDROXYETHYL Methacrylate Functionalized Single-Walled Carbon Nanotubes  

Microsoft Academic Search

Cluster-like network structures of single-walled carbon nanotubes (SWNTs) were synthesized by chemical grafting poly 2-hydroxyethyl methacrylate (polyHEMA) to the sidewalls of SWNTs. Acid chloride-functionalized tubes were coupled with commercially available HEMA monomer, which was in turn polymerized using a radical initiator. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy were used to identify the surface changes on the nanocomposites. Microscopic

Nanjundan Ashok Kumar; Sung Hun Kim; Jong Tae Kim; Kwon Taek Lim; Yeon Tae Jeong

2008-01-01

403

STUDY ON CLUSTER FORMATION OF POLY 2-HYDROXYETHYL METHACRYLATE FUNCTIONALIZED SINGLE-WALLED CARBON NANOTUBES  

Microsoft Academic Search

Cluster-like network structures of single-walled carbon nanotubes (SWNTs) were synthesized by chemical grafting poly 2-hydroxyethyl methacrylate (polyHEMA) to the sidewalls of SWNTs. Acid chloride-functionalized tubes were coupled with commercially available HEMA monomer, which was in turn polymerized using a radical initiator. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy were used to identify the surface changes on the nanocomposites. Microscopic

NANJUNDAN ASHOK KUMAR; SUNG HUN KIM; JONG TAE KIM; KWON TAEK LIM; YEON TAE JEONG

2008-01-01

404

Effects of proton irradiation on thermal stability of single-walled carbon nanotubes mat  

Microsoft Academic Search

We report effects of proton irradiation on thermal oxidation of single-walled carbon nanotubes (SWNTs). Following 400keV proton irradiation to doses of 1013–1017cm?2, thermal oxidation of SWNTs was conducted at temperatures 200–700°C. The mass of SWNTs during oxidation was monitored with thermogravimetric analysis (TGA) and ion-beam-induced structural modifications in nanotubes were characterized with Raman spectroscopy. Proton irradiation leads to enhanced thermal

A. R. Adhikari; M. B. Huang; H. Bakhru; S. Talapatra; P. M. Ajayan; C. Y. Ryu

2006-01-01

405

Pore structure of raw and purified HiPco single-walled carbon nanotubes  

Microsoft Academic Search

Very high purity single-walled carbon nanotubes (SWNTs) were obtained from HiPco SWNT samples containing Fe particles by a two-step purification process. The raw and purified samples were characterized using high resolution transmission electron microscopy (HRTEM), Raman spectroscopy and thermogravimetric analysis (TGA). The purified sample consists of ?0.4% Fe and the process does not seem to introduce any additional defects. The

Martin Cinke; Jing Li; Bin Chen; Alan Cassell; Lance Delzeit; Jie Han; M Meyyappan

2002-01-01

406

Large scale synthesis of single-wall carbon nanotubes by arc-discharge method  

Microsoft Academic Search

Using a graphite rod with a hole filled with the powder of a mixture of Y–Ni alloy and graphite or calcium carbide and nickel as anode, single-wall carbon nanotubes (SWCNTs) with high yield were produced in quantity of tens of grams a day under the arc conditions of 40?60A d.c. and helium pressure of 500 or 700torr. The yield of

Zujin Shi; Yongfu Lian; Fu Hui Liao; Xihuang Zhou; Zhennan Gu; Y. Zhang; S. Iijima; Hongdong Li; Kwok To Yue; Shu-Lin Zhang

2000-01-01

407

Thermogravimetric analysis for the array of C 60 molecules formed in single-wall carbon nanotube  

Microsoft Academic Search

The chemical stability of C60 molecules encapsulated into single-wall carbon nanotubes (SWNTs), so-called peapods, against oxygen was analyzed by thermogravimetric analysis. The maximum values for the derivative on the weight loss were observed at temperatures higher by 140 °C than that of the C60 powder and lower by 40 °C than that of SWNTs. This means that the outside SWNT

M. Zhang; M. Yudasaka; S. Bandow; S. Iijima

2003-01-01

408

Stability of ion implanted single-walled carbon nanotubes: Thermogravimetric and Raman analysis  

Microsoft Academic Search

In this work, the effect of different ions (hydrogen, helium, and neon) implanted on single-walled carbon nanotube (SWNT) is being analyzed using thermogravimetric analysis (TGA), Raman scattering, and x-ray photoelectron spectroscopy (XPS). The TGA result shows that the temperature for maximum decomposition rate (Tmax) increases at relatively low doses, i.e., by about 30 °C after hydrogen ion implantation (at the

Ananta R. Adhikari; Mengbing Huang; Hassaram Bakhru; Robert Vajtai; Chang Y. Ryu; Pulickel M. Ajayan

2006-01-01

409

Synthesis and characterization of long strands of nitrogen-doped single-walled carbon nanotubes  

Microsoft Academic Search

We describe the synthesis of N-doped single-walled carbon nanotubes (N-SWNTs), that agglomerate in bundles and form long strands (<10cm), via the thermal decomposition of ferrocene\\/ethanol\\/benzylamine (FEB) solutions in an Ar atmosphere at 950°C. The amount of benzylamine in the solution was varied from 0% to 26% by weight. Using Raman spectroscopy, we noted that as the N content is increased

F. Villalpandopaez; A. Zamudio; A. L. Elias; H. Son; E. B. Barros; S. G. Chou; Y. A. Kim; H. Muramatsu; T. Hayashi; J. Kong; H. Terrones; G. Dresselhaus; M. Endo; M. Terrones; M. S. Dresselhaus

2006-01-01

410

Preparation and mechanical characterization of laser ablated single-walled carbon-nanotubes\\/polyurethane nanocomposite microbeams  

Microsoft Academic Search

We report on the preparation of nanocomposites consisting of laser synthesized single-walled carbon nanotubes (C-SWNTs) reinforcing a polyurethane. Prior to their incorporation into the polymer matrix, the C-SWNTs were purified, and characterized by means of various techniques. The purification in nitric acid added carboxylic groups to the C-SWNTs. A procedure to properly disperse the nanomaterials in the polymer was developed

Louis Laberge Lebel; Brahim Aissa; My Ali El Khakani; Daniel Therriault

2010-01-01

411

Interaction of molecular oxygen with single-wall carbon nanotube bundles and graphite  

Microsoft Academic Search

The adsorption of oxygen on highly oriented pyrolytic graphite (HOPG) and bundles of single-wall carbon nanotubes (SWNTs) at 28 K is studied using thermal desorption spectroscopy and by a measurement of sticking probabilities. The low-coverage binding energy of oxygen adsorbed on SWNT bundles, 18.5 kJ\\/mol, is 55% higher than the low-coverage binding energy on HOPG, 12.0 kJ\\/mol. Molecular mechanics calculations

Hendrik Ulbricht; Gunnar Moos; Tobias Hertel

2003-01-01

412

Integration of enzyme immobilised single-walled carbon nanotube arrays into microfluidic devices for glucose detection  

Microsoft Academic Search

Microfluidic devices for glucose detection have been constructed and developed by integration of glucose oxidase covalently immobilised single-walled carbon nanotube arrays into a poly (dimethylsiloxane)-based microfluidic channel. This microfluidic device was tested for electrochemical glucose detection, and the results showed that the glucose can be detected with a linear response up to a concentration of 5times10-3 mol L-1. Because of

Jingxian Yu; Rudolph Le Roux; Yunfeng Gu; Kamran Yunus; Sinéad Matthews; Joe G. Shapter; A. C. Fisher

2008-01-01

413

Functionalization of single-walled carbon nanotubes using isotropic plasma treatment: Resonant Raman spectroscopy study  

SciTech Connect

Functionalization of single-walled carbon nanotubes (SWNTs) by isotropic plasma treatment was studied using resonant Raman spectroscopy. It was shown that plasma-induced functionalization results in the uniaxial isotropic constriction of the nanotubes but preserves their overall structural integrity. It was demonstrated that NH{sub 3}{center_dot}H{sub 2}O and hexamethyldisiloxan plasmas yield various types of conductivity for semiconducting SWNTs.

Utegulov, Zhandos N.; Mast, David B.; He Peng; Shi Donglu; Gilland, Robert F. [Department of Physics, University of Cincinnati, Cincinnati, Ohio 45221 (United States); Department of Chemical and Materials Engineering, University of Cincinnati, Cincinnati, Ohio 45221 (United States); Department of Electrical and Computer Engineering and Computer Science, University of Cincinnati, Cincinnati, Ohio 45221 (United States)

2005-05-15

414

Double resonant Raman phenomena enhanced by van Hove singularities in single-wall carbon nanotubes  

Microsoft Academic Search

The behavior of the disorder-induced D band in the Raman spectrum of single-wall carbon nanotubes (SWCNT's) was investigated both theoretically and experimentally. The measured maximum position of the D band for SWCNT bundles exhibits an oscillation superimposed on a linear shift, when the laser excitation energy Elaser varies in the range of 1.6-2.8 eV. We have shown theoretically by explicit

J. Kürti; V. Zólyomi; A. Grüneis; H. Kuzmany

2002-01-01

415

Thermal and Electrical Transport in Ultralow Density Single-Walled Carbon Nanotube Networks.  

PubMed

The thermal, electrical, and thermoelectric properties of aerogels of single-walled carbon nanotubes are characterized. Their ultralow density enables the transport properties of the junctions to be distinguished from those of the nanotubes themselves. Junction thermal and electrical conductances are found to be orders of magnitude larger than those found in typical dense SWCNT networks. In particular, the average junction thermal conductance is close to the theoretical maximum for a van der Waals bonded SWCNT junction. PMID:23606438

Zhang, Ke Jia; Yadav, Abhishek; Kim, Kyu Hun; Oh, Youngseok; Islam, Mohammad F; Uher, Ctirad; Pipe, Kevin P

2013-04-22

416

Stabilization of single-wall carbon nanotubes in fully sulfonated polyaniline.  

PubMed

The interaction of single wall carbon nanotubes (SWNT) with an aqueous solution of the fully sulfonated polyaniline poly(2-methoxyaniline-5-sulfonic acid) (PMAS) and (+)-1-phenylethylamine (PhEA) has been investigated using spectroscopic methods. UV-vis spectral measurements show that the PMAS backbone undergoes conformational changes upon interaction with both SWNT and PhEA. Partial intercalation of PMAS into SWNTbundles was confirmed by Raman spectroscopy and electron microscopy. PMID:15656189

in het Panhuis, Marc; Kane-Maguire, Leon A P; Moulton, Simon E; Innis, Peter C; Wallace, Gordon G

2004-11-01

417

Rectifying behaviors introduced by nitrogen-vacancy complex in spiral chirality single walled carbon nanotube device  

NASA Astrophysics Data System (ADS)

By applying nonequilibrium Green's functions in combination with density-functional theory, the effects of nitrogen-vacancy complex on electronic transport properties are investigated in spiral chirality single walled carbon nanotube device. The results show that rectifying behaviors can be tuned by introducing the complex defects with vacancy and nitrogen atoms. Moreover, current-voltage characteristics and negative differential conductance behavior can also be observed in this model. The mechanisms for these interesting phenomena are suggested.

Cheng, Caiping; Hu, Huifang; Wei, Yan; Zhang, Zhaojin; Wang, Xiaowei; Zhao, Juan; Peng, Ping

2013-08-01

418

Microwave properties of single-walled carbon nanotubes films below percolation threshold  

Microsoft Academic Search

A film residue obtained by evaporating surfactant-stabilized single-walled carbon nanotube (SWNT) suspension was characterized at 12 GHz using a scanning-sample dielectric resonator technique. Resonant frequency and quality factor changes were measured and cavity perturbation method was used to calculate the SWNT complex permittivity. The effective permittivity of the SWNT was determined as (3516-j316.5), which provided an average dielectric constant and

Chinmay Darne; Leiming Xie; Wanda Zagozdzon-Wosik; Howard K. Schmidt; Jarek Wosik

2009-01-01

419

Fabrication of Discrete Nanosized Cobalt Particles Encapsulated Inside Single-Walled Carbon Nanotubes  

SciTech Connect

Single-walled carbon nanotubes (SWNT) with encapsulated nanosized cobalt particles have been synthesized by a facile and scalable method. In this approach, SWNT were filled with a cobalt acetylacetonate solution in dichloromethane by ultrasonication. In a second step, exposure to hydrogen at different temperatures released discrete cobalt particles of controllable size inside the SWNT cavity. The SWNT-Co particles systems were characterized by transmission electron microscopy, X-ray absorption spectroscopy, Raman spectroscopy, and thermal gravimetric analysis.

Zoican Loebick, C.; Majewska, M; Ren, F; Haller, G; Pfefferle, L

2010-01-01

420

Single-walled carbon nanotubes-polymer modified graphite electrodes for DNA hybridization  

Microsoft Academic Search

Single-walled carbon nanotubes (SWCNT)-poly(vinylferrocenium) (PVF+) modified pencil graphite electrodes (PGEs) were developed in our study for the electrochemical monitoring of a sequence-selective DNA hybridization event. Firstly, SWCNT-PVF+ modified PGE, PVF+ modified PGE and unmodified PGE were characterized using scanning electron microscopy (SEM). The electrochemical behavior of these electrodes was then investigated using electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry

Mihrican Muti; Filiz Kuralay; Arzum Erdem

421

Low-temperature specific heat of single-wall carbon nanotubes  

Microsoft Academic Search

Previous low-temperature heat capacity measurements down to 2 K have been analyzed as resulting from one-dimensional quantum confinement of single-wall carbon nanotube (SWNT) vibrational modes [J. Hone et al., Science 289, 1730 (2000)]. We extended the measurements on SWNT ropes from the same preparation technique down to 0.1 K. The specific heat shows three contributions: a well-defined T-2 term from

J. C. Lasjaunias; K. Biljakovic; Z. Benes; J. E. Fischer; P. Monceau

2002-01-01

422

Adsorption of He atoms in external grooves of single-wall carbon nanotube bundles  

Microsoft Academic Search

I calculate the quantum states for He atom in the potential of an external\\u000agroove of the single wall carbon nanotube bundle. The calculated ground state\\u000aenergy is found to be in fair agreement with the experimental estimate which\\u000asuggests that the outer groove site is a preferential site for the adsorption\\u000aof He gas in the samples studied experimentally.

Antonio Šiber

2002-01-01

423

Effect of bending on single-walled carbon nanotubes: A Raman scattering study  

Microsoft Academic Search

We describe microRaman studies of serpentine single-walled carbon nanotubes grown on single-crystal quartz. Local Raman spectra were collected from bent and straight segments of the same nanotube to elucidate the effects of bending. Bending radii as large as 1-2 mum produce a measurable shift of the frequencies of the G, D, and 2D bands while the radial breathing mode remains

Bei Wang; Awnish K. Gupta; Jun Huang; Harindra Vedala; Qingzhen Hao; Vincent H. Crespi; Wonbong Choi; Peter C. Eklund

2010-01-01

424

Discrete Atom Imaging of One-Dimensional Crystals Formed Within Single-Walled Carbon Nanotubes  

Microsoft Academic Search

The complete crystallography of a one-dimensional crystal of potassium iodide encapsulated within a 1.6-nanometer-diameter single-walled carbon nanotube has been determined with high-resolution transmission electron microscopy. Individual atoms of potassium and iodine within the crystal were identified from a phase image that was reconstructed with a modified focal series restoration approach. The lattice spacings within the crystal are substantially different from

Rüdiger R. Meyer; Jeremy Sloan; Rafal E. Dunin-Borkowski; Angus I. Kirkland; Miles C. Novotny; Sam R. Bailey; John L. Hutchison; Malcolm L. H. Green

2000-01-01

425

Milestones in molecular dynamics simulations of single-walled carbon nanotube formation: A brief critical review  

Microsoft Academic Search

We present a brief review of the most important efforts aimed at simulating single-walled carbon nanotube (SWNT) nucleation\\u000a and growth processes using molecular dynamics (MD) techniques reported in the literature. MD simulations allow the spatio-temporal\\u000a movement of atoms during nonequilibrium growth to be followed. Thus, it is hoped that a successful MD simulation of the entire\\u000a SWNT formation process will

Stephan Irle; Yasuhito Ohta; Yoshiko Okamoto; Alister J. Page; Ying Wang; Keiji Morokuma

2009-01-01

426

Single-wall carbon nanotube nanobomb agents for killing breast cancer cells  

Microsoft Academic Search

We report the first application of single-wall carbon nanotubes (SWCNT) as potent therapeutic nanobomb agents for killing\\u000a breast cancer cells. We show here that by adsorbing water molecules in SWCNT sheets or loosely adsorbed on top of cells, potent\\u000a nanobombs were created that heated the water molecules inside them to more than 100?C upon exposure to laser light of 800

Balaji Panchapakesan; Shaoxin Lu; Kousik Sivakumar; Kasif Taker; Gregory Cesarone; Eric Wickstrom

2005-01-01

427

Efficient Organometallic Spin Filter between Single-Wall Carbon Nanotube or Graphene Electrodes  

Microsoft Academic Search

We present a theoretical study of spin transport in a class of molecular systems consisting of an organometallic benzene-vanadium cluster placed in between graphene or single-wall carbon-nanotube-model contacts. Ab initio modeling is performed by combining spin density functional theory and nonequilibrium Green's function techniques. We consider weak and strong cluster-contact bonds. Depending on the bonding we find from 73% (strong

Mohammad Koleini; Magnus Paulsson; Mads Brandbyge

2007-01-01

428

Solubilization of Single-Walled Carbon Nanotubes Using Ozone Generated by Dielectric Barrier Discharge  

Microsoft Academic Search

This paper describes effects of ozone (O3) concentration on water-solubility of single-walled carbon nanotubes (SWCNTs). Ozone was generated by dielectric barrier discharge (DBD) in atmospheric air with the maximum concentration of 220 ppm. Water solubility of ozone-treated SWCNTs, which was evaluated by optical absorbance of the SWCNT suspension, increased with ozone treatment time and reached the maximum in 60 min.

Wei Sun; Usama Khaled; Hironari Tomita; Zhenyu Li; Kiminobu Imasaka; Junya Suehiro

2010-01-01

429

EXAFS study of electrolytic nanosolution confined in interstitial nanospaces of single-wall carbon nanohorn colloids  

Microsoft Academic Search

The structure of RbBr aqueous solution confined in the interstitial nanospaces of single-wall carbon nanohorn (SWNH) assemblies was elucidated by using extended x-ray absorption fine structure (EXAFS) technique. The decrease of hydration number around a Rb ion is clearly observed. The EXAFS analysis indicates that the highly distorted and dehydrated structure around ions of aqueous solution confined in the nanospace

T Ohkubo; Y Hattori; H Kanoh; T Konishi; H Sakai; M Abe; D Kasuya; M Yudasaka; S Iijima; T Fujikawa; K Kaneko

2005-01-01

430

Composite materials comprising polar polymers and single-wall carbon nanotubes  

US Patent & Trademark Office Database

The invention relates to a composite comprising a weight fraction of single-wall carbon nanotubes and at least one polar polymer wherein the composite has an electrical and/or thermal conductivity enhanced over that of the polymer alone. The invention also comprises a method for making this polymer composition. The present application provides composite compositions that, over a wide range of single-wall carbon nanotube loading, have electrical conductivities exceeding those known in the art by more than one order of magnitude. The electrical conductivity enhancement depends on the weight fraction (F) of the single-wall carbon nanotubes in the composite. The electrical conductivity of the composite of this invention is at least 5 Siemens per centimeter (S/cm) at (F) of 0.5 (i.e. where single-wall carbon nanotube loading weight represents half of the total composite weight), at least 1 S/cm at a F of 0.1, at least 1.times.10.sup.-4 S/cm at (F) of 0.004, at least 6.times.10.sup.-9 S/cm at (F) of 0.001 and at least 3.times.10.sup.-16 S/cm (F) plus the intrinsic conductivity of the polymer matrix material at of 0.0001. The thermal conductivity enhancement is in excess of 1 Watt/m-.degree. K. The polar polymer can be polycarbonate, poly(acrylic acid), poly(acrylic acid), poly(methacrylic acid), polyoxide, polysulfide, polysulfone, polyamides, polyester, polyurethane, polyimide, poly(vinyl acetate), poly(vinyl alcohol), poly(vinyl chloride), poly(vinyl pyridine), poly(vinyl pyrrolidone), copolymers thereof and combinations thereof. The composite can further comprise a nonpolar polymer, such as, a polyolefin polymer, polyethylene, polypropylene, polybutene, polyisobutene, polyisoprene, polystyrene, copolymers thereof and combinations thereof.

McElrath; Kenneth O. (Houston, TX); Smith; Kenneth A. (Houston, TX); Tiano; Thomas M. (Westford, MA); Roylance; Margaret E. (West Newton, MA)

2005-08-30

431

Size-dependent polarizabilities of finite-length single-walled carbon nanotubes  

Microsoft Academic Search

Polarizabilities of single-walled carbon nanotubes with length up to 13.5 nm are studied by systematic semi-empirical PM3 calculations. Longitudinal polarizabilities increase exponentially with increasing length and about 10% higher in zigzag tubes than in armchair tubes, at least in the calculated range. The chirality-dependence of the longitudinal polarizability in finite-length nanotubes is much weaker than that in infinite-length tubes. The

Shaojie Ma; Wanlin Guo

2008-01-01

432

Structural and mechanical properties of single-wall carbon nanotube fibers  

Microsoft Academic Search

We report quantitative experimental study correlating the structure and mechanical properties of fibers made from single-walled carbon nanotubes (SWNTs) and polyvinyl alcohol (PVA). A post-synthesis solvent drawing treatment is used to vary nanotube alignment, whose detailed understanding is a prerequisite for fiber development. Quantitative analysis of nanotube alignment within the fibers with different draw ratios is performed using x-ray scattering.

V. Pichot; S. Badaire; P. A. Albouy; C. Zakri; P. Poulin; P. Launois

2006-01-01

433

Wet-spinning of neat single-walled carbon nanotube fiber from 100+% sulfuric acid  

Microsoft Academic Search

Single-Walled Carbon Nanotubes (SWNT) have been found to have excellent solubility in super acids such as 100+% H2SO4, and chlorsulfonic acid. The solutions display liquid crystalline behavior at high concentrations in super acids. Traditional wet-spinning method has been applied to SWNTs to make fibers from SWNTs only with the assistance of 100+% H2SO 4 (neat SWNT fibers). Extensive conditions, including

Fan Hua

2008-01-01

434

Charge Carrier Transport Properties in Single-Walled Carbon Nanotube Fibers  

Microsoft Academic Search

Transport properties via temperature dependences of sample resistance R(T) and influence of microwave field of 10 GHz on the conductivity of the single-walled carbon nanotubes fibers are investigated. The R(T) dependences studied within 4.2-300 K can be well approximated by the Mott law for 3D variable range hopping below T=80 K and by typical law for fluctuation-induced tunnelling model within

V. K. Ksenevich; D. Seliuta; Z. Martunas; I. Kasalynas; G. Valusis; J. Galibert; M. E. Kozlov; V. A. Samuilov

2008-01-01

435

The fabrication of polyaniline\\/single-walled carbon nanotube fibers containing a highly-oriented filler  

Microsoft Academic Search

Highly uniform composite nanofibers composed of well-oriented single-walled carbon nanotubes (SWCNTs) wrapped in a conducting polymer have been fabricated using electrospinning. Water-soluble polyaniline (WS-PANI) was used as a conducting material to improve the processability during electrospinning. The WS-PANI formed a homogeneous dispersion with the SWCNTs and poly(vinyl alcohol), and good compatibility of the WS-PANI with the SWCNTs was demonstrated by

Mi Sun Kang; Min Kyoon Shin; Yahya A. Ismail; Su Ryon Shin; Sun I. Kim; Hyunsook Kim; Haiwon Lee; Seon Jeong Kim

2009-01-01

436

Nucleation of polyvinyl alcohol crystallization by single-walled carbon nanotubes  

Microsoft Academic Search

Non-isothermal crystallization experiments were performed on poly(vinyl alcohol) mixed with single-walled carbon nanotubes. Non-isothermal crystallization experiments showed that nanotubes nucleate crystallinity at weight fractions as low as 0.1%. An Ozawa model was applied to the non-isothermal crystallization data, and this approach confirmed the results deduced from the qualitative examination of the data: there was a clear difference in crystallization kinetics

Olga Probst; Eric M. Moore; Daniel E. Resasco; Brian P. Grady

2004-01-01

437

Photoacoustic molecular imaging using single walled carbon nanotubes in living mice  

Microsoft Academic Search

Photoacoustic molecular imaging is an emerging technology offering non-invasive high resolution imaging of the molecular expressions of a disease using a photoacoustic imaging agent. Here we demonstrate for the first time the utility of single walled carbon nanotubes (SWNTs) as targeted imaging agents in living mice bearing tumor xenografts. SWNTs were conjugated with polyethylene-glycol-5000 connected to Arg-Gly-Asp (RGD) peptide to

Adam de La Zerda; Cristina Zavaleta; Shay Keren; Srikant Vaithilingam; Sunil Bodapati; Robert Teed; Zhuang Liu; Jelena Levi; Bryan R. Smith; Te-Jen Ma; Omer Oralkan; Zhen Cheng; Xiaoyuan Chen; Hongjie Dai; Butrus T. Khuri-Yakub; Sanjiv S. Gambhir

2009-01-01

438

Dynamical Structure Factors of Single-Walled Carbon Nanotubes by Means of Molecular Dynamics Calculation  

Microsoft Academic Search

For (n,n) single-walled carbon nanotubes of the so-called armchairtype , size and temperature dependence of dynamical structure factorsat the zone center and zone boundary have been studied by moleculardynamics simulations using an order-N tight-binding method.Dynamical structure factors have been calculated through the Fouriertransform of the time correlation function of the particle densityobtained from molecular dynamics simulation results.This scheme allows a

Takanori Ito; Kazume Nishidate; Mamoru Baba; Tsutomu Sato; Koichi Shindo; Kiyoshi Nishikawa

2000-01-01

439

Phonon-drag thermopower of a ballistic semiconducting single-wall carbon nanotube  

Microsoft Academic Search

We calculate the phonon-drag thermopower, Sg, in a `collision free' semiconducting single-wall carbon nanotube with the two ends attached to two electron reservoirs. In the presence of a small voltage difference DeltaV between the reservoirs we calculate the produced phonon heat flux, Q, along the axis of the nanotube. Then, Sg is simply obtained from the ratio Q\\/DeltaV by making

M. Tsaousidou; K. Papagelis

2007-01-01

440

Pore characterization of assembly-structure controlled single wall carbon nanotube  

Microsoft Academic Search

Single wall carbon nanotube (SWCNT), which has bundle structure and entangled structure, was untangled and cut by sonication\\u000a in hydrogen peroxide (H2O2) solution. The untangled state of SWCNT was examined by SEM, TEM, Raman spectroscopy and N2 adsorption. It was confirmed that the surface area of sonicated nanotubes strongly depended on the sonication time. The BET\\u000a specific surface area (SSA)

M. Arai; M. Kanamaru; T. Matsumura; Y. Hattori; S. Utsumi; T. Ohba; H. Tanaka; C. M. Yang; H. Kanoh; F. Okino; H. Touhara; K. Kaneko

2007-01-01

441

Myeloperoxidase-induced biodegradation of single-walled carbon nanotubes is mediated by hypochlorite  

Microsoft Academic Search

Broadening prospects of using single-walled carbon nanotubes (SWNTs) in medicine and biotechnology raise the concerns about\\u000a both their toxicity and the mechanisms of biodegradation and elimination from the body. SWNTs biodegradation as a result of\\u000a catalytic activity of myeloperoxidase (MPO) was shown in the isolated MPO system as well as in the suspension of neutrophils\\u000a [Kagan V.E. et al., 2010].

I. I. Vlasova; A. V. Sokolov; A. V. Chekanov; V. A. Kostevich; V. B. Vasilyev

2011-01-01

442

Non-destructive optical characterization of DNA-wrapping of single-walled carbon nanotubes  

Microsoft Academic Search

Single-stranded DNA can form a stable hybrid structure with a single-walled carbon nanotube, allowing dispersion of individual nanotubes in aqueous solution and facilitating the development of methods to separate nanotubes by type. Optical and electronic properties of specific DNA-nanotube structures are the focus of our study due to potential optoelectronic device applications. Within a semi-empirical tight-binding approach, we have studied

S. E. Snyder; S. V. Rotkin

2008-01-01

443

Synthesis, electronic structure, and Raman scattering of phosphorous-doped single-wall carbon nanotubes  

SciTech Connect

Substitutional phosphorous doping in single-wall carbon nanotubes (SWNTs) is investigated by density functional theory and resonance Raman spectroscopy. Electronic structure calculations predict charge localization on the phosphorus atom, which is also responsible of generating non-dispersive valence and conduction bands close to the Fermi level. Analysis of electron and phonon renormalization in the double-resonance Raman process confirms the different nature of the phosphorous donor doping (localized) when compared to nitrogen substitutional doping (non-localized) in SWNTs.

Sumpter, Bobby G [ORNL; Cruz Silva, Eduardo [ORNL; Meunier, Vincent [ORNL; Terrones Maldonado, Humberto [ORNL; Terrones Maldonado, Mauricio [ORNL; Campos-Delgado, Jessica [IPICyT; Jorio, Ado [Universidade Federal de Minas Gerais; Pimenta, M. A. [Universidade Federal de Minas Gerais; Rao, A. M. [Clemson University; Maciel, I. O. [Universidad Federal de Minas Gerais

2009-01-01

444

Aquatic toxicity assessment of single-walled carbon nanotubes using zebrafish embryos  

Microsoft Academic Search

Zebrafish embryos selected at the 64-cell stage were exposed to various concentrations of amide functionalized single-walled carbon nanotubes (SWCNTs) ranging from 1 to 10 mug\\/ml dissolved in 1% Pluronic F-68 (a cell culture grade surfactant), and the development of embryos was examined from 24 to 120 hours post fertilization (hpf). Incubation of embryos in 1% F-68 did not induce overt

Huichin Pan; Yu-Jun Lin; Meng-Wei Li; Han-Ni Chuang; Cheng-Chung Chou

2011-01-01

445

Covalent sidewall functionalization of single-walled carbon nanotubes by amino acids  

Microsoft Academic Search

Single-walled carbon nanotubes (SWNTs) with amino acids covalently attached to their side walls, viz., “nanotube-aminoacids,” have been prepared starting from colloidal solutions of fluorinated SWNTs (F-SWNTs) and amino acids\\u000a in o-dichlorobenzene and heating at 80–150 °C in the presence of pyridine. The syntheses were carried out with the F-SWNTs of\\u000a approximately 2: 1 (C: F) stoichiometry and several natural ?-aino

M. X. Pulikkathara; V. N. Khabashesku

2008-01-01

446

Two-electron and four-electron periodicity in single-wall carbon nanotube quantum dots  

Microsoft Academic Search

Single quantum dots have been fabricated in single-wall carbon nanotubes and electrical transport properties have been measured at low temperature. Two- and four-electron periodicities have been clearly observed in the same sample in different gate voltage ranges. The former is an even–odd effect which originates from the spin degeneracy, while the latter is related to the additional two-fold band degeneracy.

Tomoko Fuse; Satoshi Moriyama; Yoshinobu Aoyagi; Masaki Suzuki; Koji Ishibashi

2003-01-01

447

Electrical properties and devices of large-diameter single-walled carbon nanotubes  

Microsoft Academic Search

Individual large-diameter (~3 to 5 nm) semiconducting single-walled carbon nanotubes (SWNTs) are found to exhibit ambipolar field-effect transistor (FET) behavior, with easily accessible n- and p-conduction channels by simple electrostatic gates. The effects of temperature and ultraviolet radiation on their electrical properties are elucidated, shedding light into the intrinsic behavior of SWNTs in this relatively large-diameter regime. The ambipolar SWNT-FETs

Ali Javey; Moonsub Shim; Hongjie Dai

2002-01-01

448

Covalently ?-cyclodextrin modified single-walled carbon nanotubes: a novel artificial receptor synthesized by ‘click’ chemistry  

Microsoft Academic Search

Novel ?-cyclodextrin covalently modified single-walled carbon nanotubes have been synthesized via a ‘click’ coupling reaction.\\u000a The product was fully characterized with Raman, FTIR, XRD, UV-Vis-NIR spectra as well as TEM and TGA measurements. The effective\\u000a functionalization via ‘click’ coupling has set up a facile and versatile route for modular preparation of SWNTs based functional\\u000a materials. The inclusion complexation behavior of

Zhen Guo; Li Liang; Jia-Jie Liang; Yan-Feng Ma; Xiao-Ying Yang; Dong-Mei Ren; Yong-Sheng Chen; Jian-Yu Zheng

2008-01-01

449

Chemical vapor deposition of methane for single-walled carbon nanotubes  

Microsoft Academic Search

We report the synthesis of high-quality single-walled carbon nanotubes (SWNT) by chemical vapor deposition (CVD) of methane at 1000°C on supported Fe2O3 catalysts. The type of catalyst support is found to control the formation of individual or bundled SWNTs. Catalysts supported on crystalline alumina nanoparticles produce abundant individual SWNTs and small bundles. Catalysts supported by amorphous silica particles produce only

Jing Kong; Alan M. Cassell; Hongjie Dai

1998-01-01

450

Single-walled carbon nanotubes produced by plasma-enhanced chemical vapor deposition  

Microsoft Academic Search

Single-walled carbon nanotubes (SWNTs) are produced for the first time using plasma-enhanced chemical vapor deposition method. In this method, not only SWNTs in the form of thin bundles but also individually grown SWNTs are produced at a quite low-synthesis temperature (550 °C). According to analyses by field emission gun transmission electron microscopy and Raman scattering spectroscopy, it is conjectured that

Toshiaki Kato; Goo-Hwan Jeong; Takamichi Hirata; Rikizo Hatakeyama; Kazuyuki Tohji; Kenichi Motomiya

2003-01-01

451

Single-Walled Carbon Nanotube Paper as a Sorbent for Organic Vapor Preconcentration  

SciTech Connect

Single-walled carbon nanotubes in paper form are characterized as an adsorptive material for a thermally-desorbed preconcentrator for organic vapors. Adsorbed vapors were released by a temperature programmed desorption method and detected downstream. The tested vapors, methyl ethyl ketone, toluene, and dimethyl methylphosphonate were released from the packed column at different temperatures and simple mixtures could be partially separated by the thermal desorption process.

Zheng, Feng; Baldwin, David L.; Fifield, Leonard S.; Anheier, Norman C.; Aardahl, Chris L.; Grate, Jay W.

2006-03-02

452

Absolute potential of the Fermi level of single-walled carbon nanotubes via hydrogenase complex formation  

Microsoft Academic Search

The absolute potential of the Fermi level of nanotubes as a function of nanotube type is not presently understood, and is important for many nanotube applications and sorting strategies. Here, we study complexes of recombinant [FeFe] hydrogenases and single-walled carbon nanotubes. We find evidence that novel charge-transfer complexes are formed and are stable, which enables further study and application of

Timothy McDonald; Drazenka Svedruzic; Yong-Hyun Kim; Jeffrey Blackburn; Shengbai Zhang; Paul King; Michael Heben

2007-01-01

453

Controlling the electronic properties of single-wall carbon nanotubes by chemical doping  

NASA Astrophysics Data System (ADS)

Single-wall carbon nanotube bulk material can be reversibly doped by redox reactions between the material and solutions of organic radical-anions, with Li + as a counter ion. The shift of the Fermi level induced by the redox reactions determines both the electrical conductivity and the chemical composition of the doped material. The reported results show that there is no stage of intercalation into the material.

Jouguelet, E.; Mathis, C.; Petit, P.

2000-03-01

454

Flexible, transparent single-walled carbon nanotube transistors with graphene electrodes.  

PubMed

This paper reports a mechanically flexible, transparent thin film transistor that uses graphene as a conducting electrode and single-walled carbon nanotubes (SWNTs) as a semiconducting channel. These SWNTs and graphene films were printed on flexible plastic substrates using a printing method. The resulting devices exhibited a mobility of ? 2 cm(2) V(-1) s -1), On/Off ratio of ? 10(2), transmittance of ? 81% and excellent mechanical bendability. PMID:20858937

Jang, Sukjae; Jang, Houk; Lee, Youngbin; Suh, Daewoo; Baik, Seunghyun; Hong, Byung Hee; Ahn, Jong-Hyun

2010-09-22

455

X-ray photoemission spectroscopy study of fluorinated single-walled carbon nanotubes  

Microsoft Academic Search

We have investigated the change of atomic and electronic structures of fluorinated single-walled carbon nanotubes (SWCNTs) using x-ray photoemission spectroscopy (XPS), electrical resistivity measurements, and transmission electron microscopy (TEM). The fluorine content increases with increasing reaction temperature up to 300 °C. XPS indicated that the fluorinated SWCNT reveals an ionic-bonding character at low concentration and covalent-bonding character at high concentration.

Kay Hyeok An; Jeong Goo Heo; Kwan Goo Jeon; Dong Jae Bae; Chulsu Jo; Cheol Woong Yang; Chong-Yun Park; Young Hee Lee; Young Seak Lee; Young Su Chung

2002-01-01

456

Temperature Dependence of Electron to Lattice Energy-Transfer in Single-Wall Carbon Nanotube Bundles  

Microsoft Academic Search

The electron-phonon coupling strength in single-wall carbon nanotube (SWNT) bundles has been studied directly in the time-domain by femtosecond time-resolved photoelectron spectroscopy. We have measured the dependence of H(T_e,T_l), the rate of energy-transfer between the electronic system and the lattice as a function of electron and lattice temperatures T_e and T_l. The experiments are consistent with a T^5 dependence of

G. Moos; R. Fasel; T. Hertel

2002-01-01

457

Fibers of aligned single-walled carbon nanotubes: Polarized Raman spectroscopy  

Microsoft Academic Search

To probe the one-dimensional nature of single-wall carbon nanotubes (SWNTs) in bulk samples, we have devised a simple method for generating fibers of aligned SWNTs. We measured polarization-dependent Raman spectra on the oriented fibers. Contrary to what is expected from their theoretically assigned vibration-mode symmetries, all the Raman line intensities are observed to decrease in nearly equal amounts for the

H. H. Gommans; J. W. Alldredge; H. Tashiro; J. Magnuson; A. G. Rinzler

2000-01-01

458

Effect of residual catalyst on the vibrational modes of single-walled carbon nanotubes  

SciTech Connect

Raman scattering measurements of single-walled carbon nanotubes prepared by laser ablation with Ni/Co catalyst show that samples that have not been purified have a graphitic mode frequency that is 8 cm{sup -1} lower than that of samples from which most of the catalyst has been removed. The shift is attributed to charge transfer from the catalyst particles to the nanotubes. The charge transfer from the residual catalyst also affects the temperature dependence of the radial breathing mode.

McNeil, L.E.; Park, H.; Lu, J.P.; Peters, M.J. [Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3255 (United States); Department of Physics and Astronomy, Appalachian State University, Boone, North Carolina 28608 (United States)

2004-11-01

459

Transfer matrix approach to quantum conductivity calculations in single-wall carbon nanotubes  

Microsoft Academic Search

We present an efficient transfer matrix formalism for obtaining the quantum conductivity of single-wall carbon nanotubes (SWCN's) based on a nonorthogonal tight-binding scheme. The formalism is used to calculate conductivity in the presence of topological defects and H adsorbates. I-V characteristics show large oscillatory behavior as a function of the number of H adatoms for both (10,0) and (5,5) SWCN's.

Antonis N. Andriotis; Madhu Menon; Deepak Srivastava

2002-01-01

460

Molecular Ordering of Organic Molten Salts Triggered by Single-Walled Carbon Nanotubes  

Microsoft Academic Search

When mixed with imidazolium ion-based room-temperature ionic liquid, pristine single-walled carbon nanotubes formed gels after being ground. The heavily entangled nanotube bundles were found to untangle within the gel to form much finer bundles. Phase transition and rheological properties suggest that the gels are formed by physical cross-linking of the nanotube bundles, mediated by local molecular ordering of the ionic

Takanori Fukushima; Atsuko Kosaka; Yoji Ishimura; Takashi Yamamoto; Toshikazu Takigawa; Noriyuki Ishii; Takuzo Aida

2003-01-01

461

Capacitance properties of single wall carbon nanotube\\/polypyrrole composite films  

Microsoft Academic Search

The electrochemical capacitance properties of composite films prepared from electrically conducting polypyrrole (PPy) and single wall carbon nanotubes (SWNTs) have been investigated for supercapacitor application. The composite films were electropolymerized from homogenous mixture of pyrrole (Py) and raw SWNTs, or suspension of Py and functionalized SWNTs. The SWNTs were functionalized and cut by suspending in concentrated H2SO4\\/HNO3 solution and sonicating

Jie Wang; Youlong Xu; Xi Chen; Xiaofei Sun

2007-01-01

462

Flexible Single-wall Carbon Nanotube Membrane Symmetric Aqueous Double Layer Electrochemical Capacitor  

NASA Astrophysics Data System (ADS)

We present preliminary results on an aqueous symmetric double layer electrochemical capacitor (EDLC) constructed with flexible binder-free single wall carbon (SWCNTs) membrane as electrodes. The capacitors were cycled from 0 to 1V @ 10 A/g for 10,000 cycles with 99.9% coulombic efficiency and 94% energy efficiency, and 100% depth of discharge. The power performance of the aqueous symmetric SWCNTs membrane capacitor is almost 100 --1000 times better than commercial non-aqueous EDLC capacitors.

Shetty, Pralav; Kapulson, Jim; Rajagopalan, Ramakrishnan; Adu, Kofi

2012-02-01

463

Selective Growth of Well-Aligned Semiconducting Single-Walled Carbon Nanotubes  

Microsoft Academic Search

High-density arrays of perfectly aligned single-walled carbon nanotubes (SWNTs) consisting almost exclusively of semiconducting nanotubes were grown on ST-cut single crystal quartz substrates. Raman spectroscopy together with electrical measurements of field effect transistors (FETs) fabricated from the as-grown samples showed that over 95% of the nanotubes in the arrays are semiconducting. The mechanism of selective growth was explored. It is

Lei Ding; Alexander Tselev; Jinyong Wang; Dongning Yuan; Haibin Chu; Thomas P. McNicholas; Yan Li; Jie Liu

2009-01-01

464

Tunneling energy barriers of emitted electrons in single-walled carbon nanotubes  

Microsoft Academic Search

By use of the first-principles calculations, we systematically investigate and demonstrate the localized characteristics of electronic wave functions, corresponding to quantized energy levels in the vicinity of the Fermi level, in one individual finite-length single-walled carbon nanotube. Within the framework of the energy levels emission model, quantized energy levels relevant to electron emission are considered, and the corresponding tunneling energy

Gang Zhou; Jian Wu; Wenhui Duan; Binglin Gu

2004-01-01

465

Effect of sigma electrons on the pi-electron behavior in single-wall carbon nanotubes  

Microsoft Academic Search

The hybrid orbitals of single-wall carbon nanotubes are given according to\\u000athe structure of the nanotube. Because the energy levels of these hybrid\\u000aorbitals are close to each other, the sigma-orbitals will affect the behavior\\u000aof the pi-electrons, which is called the scattering of pi- electrons. This\\u000ascattering effect is taken into account in the nanotube and the local wave

G.-P. Tong; Q.-P. Huang

2008-01-01

466

Effect of sigma electrons on the pi-electron behavior in single-wall carbon nanotubes  

Microsoft Academic Search

The hybrid orbitals of single-wall carbon nanotubes are given according to the structure of the nanotube. Because the energy levels of these hybrid orbitals are close to each other, the sigma-orbitals will affect the behavior of the pi-electrons, which is called the scattering of pi- electrons. This scattering effect is taken into account in the nanotube and the local wave

G.-P. Tong; Q.-P. Huang

2008-01-01

467

Atomistic dynamics of deformation, fracture, and joining of individual single-walled carbon nanotubes  

Microsoft Academic Search

The tensile deformation process of individual single-walled carbon nanotubes (SWCNTs) was in situ observed with measurements of the mechanical properties by transmission electron microscopy combined with the functions of scanning probe microscopy. The values of Young's modulus, tensile stress and strain at the fracture of SWCNTs are 950±130GPa , 25±1GPa , and 0.30±0.03 , respectively. It was shown that two

Koji Asaka; Tokushi Kizuka

2005-01-01

468

Transmission electron microscopy observations of fracture of single-wall carbon nanotubes under axial tension  

Microsoft Academic Search

Well-aligned bundles of single-wall carbon nanotubes under tensile stresses were observed to fracture in real-time by transmission electron microscopy. The expansion of elliptical holes in the polymer matrix results in a tensile force in bridging nanotubes. The polymer matrix at both ends of the bundles deforms extensively under the tension force, and fracture of the nanotubes occurs in tension within

O. Lourie; H. D. Wagner

1998-01-01