Résumé
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.