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Journal ArticleDOI

Band gap fluorescence from individual single-walled carbon nanotubes.

26 Jul 2002-Science (American Association for the Advancement of Science)-Vol. 297, Iss: 5581, pp 593-596
TL;DR: At pH less than 5, the absorption and emission spectra of individual nanotubes show evidence of band gap–selective protonation of the side walls of the tube, which is readily reversed by treatment with base or ultraviolet light.
Abstract: 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 with metallic tubes and substantially broadens the absorption spectra. At pH less than 5, the absorption and emission spectra of individual nanotubes show evidence of band gap-selective protonation of the side walls of the tube. This protonation is readily reversed by treatment with base or ultraviolet light.
Citations
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Journal ArticleDOI
TL;DR: In this article, the authors focus on the origin of the D and G peaks and the second order of D peak and show that the G and 2 D Raman peaks change in shape, position and relative intensity with number of graphene layers.

6,496 citations

Journal ArticleDOI
TL;DR: Department of Materials Science, University of Patras, Greece, Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, and Dipartimento di Scienze Farmaceutiche, Universita di Trieste, Piazzale Europa 1, 34127 Triesteadays.
Abstract: Department of Materials Science, University of Patras, 26504 Rio Patras, Greece, Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, 48 Vass. Constantinou Avenue, 116 35 Athens, Greece, Institut de Biologie Moleculaire et Cellulaire, UPR9021 CNRS, Immunologie et Chimie Therapeutiques, 67084 Strasbourg, France, and Dipartimento di Scienze Farmaceutiche, Universita di Trieste, Piazzale Europa 1, 34127 Trieste, Italy

3,886 citations

Journal ArticleDOI
TL;DR: The use of Raman spectroscopy to reveal the remarkable structure and the unusual electronic and phonon properties of single wall carbon nanotubes (SWNTs) is reviewed comprehensively in this article.

3,835 citations

Journal ArticleDOI
20 Dec 2002-Science
TL;DR: Optical spectroscopy can be used to rapidly determine the detailed composition of bulk SWNT samples, providing distributions in both tube diameter and chiral angle.
Abstract: Spectrofluorimetric measurements on single-walled carbon nanotubes (SWNTs) isolated in aqueous surfactant suspensions have revealed distinct electronic absorption and emission transitions for more than 30 different semiconducting nanotube species. By combining these fluorimetric results with resonance Raman data, each optical transition has been mapped to a specific (n,m) nanotube structure. Optical spectroscopy can thereby be used to rapidly determine the detailed composition of bulk SWNT samples, providing distributions in both tube diameter and chiral angle. The measured transition frequencies differ substantially from simple theoretical predictions. These deviations may reflect combinations of trigonal warping and excitonic effects.

2,861 citations

Journal ArticleDOI
TL;DR: It is demonstrated that DNA-coated carbon nanotubes can be separated into fractions with different electronic structures by ion-exchange chromatography, and opens the door to carbon-nanotube-based applications in biotechnology.
Abstract: Carbon nanotubes are man-made one-dimensional carbon crystals with different diameters and chiralities. Owing to their superb mechanical and electrical properties, many potential applications have been proposed for them. However, polydispersity and poor solubility in both aqueous and non-aqueous solution impose a considerable challenge for their separation and assembly, which is required for many applications. Here we report our finding of DNA-assisted dispersion and separation of carbon nanotubes. Bundled single-walled carbon nanotubes are effectively dispersed in water by their sonication in the presence of single-stranded DNA (ssDNA). Optical absorption and fluorescence spectroscopy and atomic force microscopy measurements provide evidence for individually dispersed carbon nanotubes. Molecular modelling suggests that ssDNA can bind to carbon nanotubes through pi-stacking, resulting in helical wrapping to the surface. The binding free energy of ssDNA to carbon nanotubes rivals that of two nanotubes for each other. We also demonstrate that DNA-coated carbon nanotubes can be separated into fractions with different electronic structures by ion-exchange chromatography. This finding links one of the central molecules in biology to a technologically very important nanomaterial, and opens the door to carbon-nanotube-based applications in biotechnology.

2,620 citations


Cites background from "Band gap fluorescence from individu..."

  • ...These features are characteristic of individually dispersed nanotube solutions, obtained only recently with surfactants after rather more intense sonication treatmen...

    [...]

References
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Journal ArticleDOI
TL;DR: The CHARMM (Chemistry at Harvard Macromolecular Mechanics) as discussed by the authors is a computer program that uses empirical energy functions to model macromolescular systems, and it can read or model build structures, energy minimize them by first- or second-derivative techniques, perform a normal mode or molecular dynamics simulation, and analyze the structural, equilibrium, and dynamic properties determined in these calculations.
Abstract: CHARMM (Chemistry at HARvard Macromolecular Mechanics) is a highly flexible computer program which uses empirical energy functions to model macromolecular systems. The program can read or model build structures, energy minimize them by first- or second-derivative techniques, perform a normal mode or molecular dynamics simulation, and analyze the structural, equilibrium, and dynamic properties determined in these calculations. The operations that CHARMM can perform are described, and some implementation details are given. A set of parameters for the empirical energy function and a sample run are included.

14,725 citations

Journal ArticleDOI
TL;DR: The MOLSCRIPT program as discussed by the authors produces plots of protein structures using several different kinds of representations, including simple wire models, ball-and-stick models, CPK models and text labels.
Abstract: The MOLSCRIPT program produces plots of protein structures using several different kinds of representations. Schematic drawings, simple wire models, ball-and-stick models, CPK models and text labels can be mixed freely. The schematic drawings are shaded to improve the illusion of three dimensionality. A number of parameters affecting various aspects of the objects drawn can be changed by the user. The output from the program is in PostScript format.

13,971 citations

Journal ArticleDOI
26 Jul 1996-Science
TL;DR: X-ray diffraction and electron microscopy showed that fullerene single-wall nanotubes (SWNTs) are nearly uniform in diameter and that they self-organize into “ropes,” which consist of 100 to 500 SWNTs in a two-dimensional triangular lattice with a lattice constant of 17 angstroms.
Abstract: The major part of this chapter has already appeared in [1], but because of the length restrictions (in Science), the discussion on why we think this form is given in only brief detail. This chapter goes into more depth to try to answer the questions of why the fullerenes form themselves. This is another example of the very special behavior of carbon. From a chemist’s standpoint, it is carbon’s ability to form multiple bonds that allows it to make these low dimensional forms rather than to produce tetrahedral forms. Carbon can readily accomplish this and it is in the mathematics and physics of the way this universe was put together, that carbon is given this property. One of the consequences of this property is that, if left to its own devices as carbon condenses from the vapor and if the temperature range is just right, above 1000°C, but lower than 1400°C, there is an efficient self-assembly process whose endpoint is C60.

5,215 citations

Book
01 Jan 1996
TL;DR: In this paper, the authors present a detailed overview of the properties of Fullerenes and their properties in surface science applications, such as scanning tunnel microscopy, growth and fragmentation studies, and chemical synthesis.
Abstract: Historical Introduction. Carbon Materials. Structure of Fullerenes. Symmetry Considerations. Growth and Fragmentation Studies. Crystalline Structure of Fullerenes. Synthesis of Fullerene Molecules and Solids. Doping of Fullerenes. Structure of Doped Fullerenes and Fullerene Compounds. Fullerene Chemistry. Vibrational Modes. Thermal Properties. Electronic Structure. Optical Properties. Electrical and Thermal Properties. Superconductivity. Nuclear Magnetic Resonance Studies. Electron Paramagnetic Resonance. Surface Science Techniques on Fullerenes. Magnetic Properties. Fullerene-Related Tubules and Spherules. Scanning Tunnel Microscopy. Applications.

4,008 citations


"Band gap fluorescence from individu..." refers background in this paper

  • ...Single-walled carbon nanotubes are elongated members of the fullerene family (1) that are currently the focus of intense multidisciplinary study because of their unique physical and chemical properties and their prospects for practical applications (2)....

    [...]

Journal ArticleDOI
TL;DR: In this paper, a new method for performing molecular dynamics simulations under constant pressure is presented, which is based on the extended system formalism introduced by Andersen, the deterministic equations of motion for the piston degree of freedom are replaced by a Langevin equation; a suitable choice of collision frequency then eliminates the unphysical "ringing" of the volume associated with the piston mass.
Abstract: A new method for performing molecular dynamics simulations under constant pressure is presented. In the method, which is based on the extended system formalism introduced by Andersen, the deterministic equations of motion for the piston degree of freedom are replaced by a Langevin equation; a suitable choice of collision frequency then eliminates the unphysical ‘‘ringing’’ of the volume associated with the piston mass. In this way it is similar to the ‘‘weak coupling algorithm’’ developed by Berendsen and co‐workers to perform molecular dynamics simulation without piston mass effects. It is shown, however, that the weak coupling algorithm induces artifacts into the simulation which can be quite severe for inhomogeneous systems such as aqueous biopolymers or liquid/liquid interfaces.

3,799 citations