We have studied the trigonal warping effect in metallic carbon nanotubes using resonance Raman scattering and examining the G0-band profile for individual metallic single-wall carbon nanotubes. We show that the observed splitting in the G0-band phonon spectra is directly correlated with the splitting in the singularities of the joint density of electronic states, i.e., detailed information abou...

Based on the continuum mechanics and a multiple-elastic beam model, the nonlinear free vibration of embedded multiwall carbon nanotubes considering intertube radial displacement and the related internal degrees of freedom is investigated. By using the incremental harmonic balanced method, the iterative relationship of nonlinear amplitude and frequency for the single-wall nanotube and double-wal...

We have carried out systematic calculations for hydrogen-adsorption and -storage mechanism in carbon nanotubes at zero temperature. Hydrogen atoms first adsorb on the tube wall in an arch-type and zigzag-type up to a coverage of theta = 1.0 and are stored in the capillary as a form of H(2) molecule at higher coverages. Hydrogen atoms can be stored dominantly through the tube wall by breaking th...

We investigate the nitrogen substitutional impurity in semiconducting zigzag and metallic armchair single-wall carbon nanotubes using ab initio density functional theory. At low concentrations (less than 1 at. %), the defect state in a semiconducting tube becomes spatially localized and develops a flat energy level in the band gap. Such a localized state makes the impurity site chemically and e...

We present preliminary results of Raman scattering measurements of multiwall carbon nanotubes (MWCNT). The nanotubes have been carefully dissolved, separated and then characterized by AFM. The micro-Raman spectra of the objects are taken with 514,5nm wavelength excitations and in the temperature range 4K 400K. Basically the spectra are quite similar to the well known single wall carbon nanotube...

The unusual one-dimensional properties of phonons in crystalline arrays of carbon nanotubes is presented. The main technique for probing the phonon spectra is Raman spectroscopy and the many unique and unusual features of the Raman spectra of carbon nanotubes are highlighted. Various features of the first-order Raman spectra are emphasized, with regard to their 1D behavior and special character...

in this paper, we have used density functional perturbation theory (dfpt) and pseudo-potential method to calculate the phonon spectrum, phonon density of states (dos), specific heat capacity and mechanical properties of (5,5) armchair and (9,0) zigzag single wall carbon nanotubes (swcnts). our calculations show that young’s modulusfor (5,5) and (9,0) nanotubesare higher than 1tpa. we have also ...

Density-functional theory is used to investigate sulfur dioxide physisorption inside and outside of single-wall carbon nanotube of (5,0) and (5,5). This study is conducted at B3LYP/6-31G* level of theory. Sulfur dioxide molecule is studied with axis oriented parallel or perpendicular to the nanotube wall. Both internal and external adsorption on nanotubes is increased with the angle of interact...

A review is presented of one-dimensional cutting lines that are utilized to obtain the physical properties of carbon nanotubes from the corresponding properties of graphite by the zone-folding scheme. Quantization effects in general low-dimensional systems are briefly discussed, followed by a more detailed consideration of one-dimensional single-wall carbon nanotubes. The geometrical structure ...

Carbon nanotubes focus the attention of many scientists because of their huge potential of industrial applications, but there is a paucity of information on the toxicological properties of this material. The aim of this experimental study was to characterize the biological reactivity of purified multi-wall carbon nanotubes in the rat lung and in vitro. Multi-wall carbon nanotubes (CNT) or groun...