A. Righi

Excitation energy dependence of the Raman spectrum of single-walled carbon nanotubes

We investigate the excitation energy dependence of Raman modes in the 600–1200 cm−1 range. The main features are first, two lines around 860 and 1060 cm−1 independent of the energy and second, energy-dependent couples of lines, each of them composed of one first-order mode and one substractive combination band. In each couple, the frequency of the lines is found to follow a linear, strong and opposite energy dependence.

Gas and pressure effects on the production of single-walled carbon nanotubes by laser ablation

Abstract We report the production of single-walled carbon nanotubes (SWNTs) under argon, nitrogen and helium atmospheres in the pressure range of 50 to 500 Torr using a continuous wave 10.6-μm CO 2 -laser. Both argon and nitrogen can be equally used as buffer gas to synthesize SWNTs in high yield between 200 and 400 Torr. Below 200 Torr the amount of SWNTs in the soot is drastically decreased and the material is dominated by amorphous carbon. Negligible amounts of SWNTs were formed using helium. These gas and pressure effects are assigned to changes on the local temperature environment.

The influence of the target composition in the structural characteristics of single-walled carbon nanotubes produced by laser ablation

We report the production of single-walled carbon nanotubes (SWNTs) using a CO 2 -laser operating in continuous wave (cw) mode. The influence of the target composition as important parameter in the production of SWNTs is studied. Here, Raman spectroscopy is a valuable tool and a detailed analysis of various Raman experiments reveals that the target composition not only determines the content of SWNTs in the synthesized materials but as well their structural features, especially the diameter distribution.

Raman study of orientational order in fibers of single wall carbon nanotubes

Polarized Raman spectroscopy is used to study orientational order and resonance in fibers of SWNT. The polarized Raman intensity follows essentially the same angle dependence for both radial breathing mode and tangential modes and for both semi-conducting and metallic nanotubes. A simple resonant model is proposed, which provides good fits of two sets of data for two different fibers.

Single-wall carbon nanotubes: Study of production parameters using cw CO2-laser ablation technique

We report the production of single-wall carbon nanotubes (SWNTs) using a continuous wave (cw) 10.6 μm CO2-laser. A wide range of experimental parameters and their influence on the formation of SWNTs has been investigated. It turns out that the temperature environment near the zone of evaporation plays a key role in the growth process of SWNTs. This result has important consequences for the optimization of the production of SWNTs.

Incorporation of Multi Wall Carbon Nanotubes into Glass-Surfaces via Laser-Treatment

Carbon nanotubes (CNT) are interesting candidates for the reinforcement in robust composites and for conducting fillers in polymers due to their fascinating electronic and mechanical properties. For the first time, we report the incorporation of multi walled carbon nanotubes (MWNTs) into silica-glass surfaces by means of partial surface-melting caused by a continuous wave Nd:YAG laser. MWNTs were detected being well incorporated in the silica-surface. The composites are characterized using scanning electron microscopy (SEM) and Raman-spectroscopy. A model for the composite-formation is proposed based on heatabsorption by MWNTs and a partial melting of the silica-surface.