in this work the conduction of ion-water solution through two discrete bundles of armchair carbon and silicon carbide nanotubes, as useful membranes for water desalination, is studied. in order that studies on different types of nanotubes be comparable, the chiral vectors of c and si-c nanotubes are selected as (7,7) and (5,5), respectively, so that    a similar volume of fluid is investigated ...

Single- and multiwalled carbon nanotubes have been covalently functionalized with free-base porphyrin. The quantity of porphyrin linked to the surface was determined from thermogravimetric and UV-vis analysis. A reversible protonation equilibrium between the attached porphyrin and the residual acid groups of the carbon nanotubes has been identified. Steady-state fluorescence emission spectrum o...

Tunable Raman spectroscopy is used to measure the optical transition energies Eii of individual single wall carbon nanotubes. Eii is observed to shift down in energy by as much as 50 meV, from -160 to 300 degrees C, in contrast with previous measurements performed on nanotubes in alternate environments, which show upshifts and downshifts in Eii with temperature. We determine that electron-phono...

In this work, we probed the effects of shear flow on the alignment of dispersed single-walled carbon nanotubes in polymer solutions. Two different systems were compared: Single-walled carbon nanotubes dispersed using an anionic surfactant and single-walled carbon nanotubes dispersed using an anionic surfactant and a weakly binding polymer. It was determined that the addition of the weakly bindi...

Here we present a hybrid approach to functionalize multi-walled carbon nanotubes in aqueous solution, exploring a non-covalent binding strategy. We focus on formation of hybrid complexes consisting of carbon nanotubes decorated by single stranded DNA, non-covalently attached using surfactants as intermediate layers. Unlike single walled carbon nanotubes, revealing easy side wall wrapping of DNA...

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 a...

Multi-walled carbon nanotubes are dispersed in water via the formation of adducts with dyes, where the process may be monitored by the visual observation of colour variations of dye solutions. Atomic force microscopy images corroborate evidence for attachment of dyes on nanotubes. Laser Raman and Fourier transform infrared spectroscopies suggest intimate electronic interactions between nanotube...

Metallic and semiconducting carbon nanotubes generally coexist in as-grown materials. We present a gas-phase plasma hydrocarbonation reaction to selectively etch and gasify metallic nanotubes, retaining the semiconducting nanotubes in near-pristine form. With this process, 100% of purely semiconducting nanotubes were obtained and connected in parallel for high-current transistors. The diameter-...

We use electrostatic force microscopy and scanned gate microscopy to probe the conducting properties of carbon nanotubes at room temperature. Multiwalled carbon nanotubes are shown to be diffusive conductors, while metallic single-walled carbon nanotubes are ballistic conductors over micron lengths. Semiconducting single-walled carbon nanotubes are shown to have a series of large barriers to co...

We have fabricated field-effect transistors from carbon nanotubes using a novel selective placement scheme. We use carbon nanotubes that are covalently bound to molecules containing a hydroxamic acid functionality. The functionalized nanotubes bind strongly to basic metal oxide surfaces, but not to silicon dioxide. Upon annealing, the functionalization is removed, restoring the electronic prope...