KrF excimer laser ablation in helium yields the highest amount of SWCNTs over other inert gases

The single-wall carbon nanotubes (SWCNTs) were synthesized using the equipment, method and experimental conditions described in [1]. Starting from the results shown in [2] and [3] we studied the influence of inert carrier gas over ablated mass, collected material, conducting character of SWCNTs and diameter distribution of SWCNTs. In our study KrF 248nm excimer laser was used instead of Nd:YAG (532nm) in [2] and four ablation gases: argon, nitrogen, neon and helium were involved. This kind of study, performed in our experimental conditions, was not reported so far. The ablated products were characterized using Raman spectroscopy and thermogravimetric analysis. We observed linear decrease of ablated mass with the increase of carrier gas molecular mass. Also the collected mass follows the same trend. TGA allowed us to calculate the mass of SWCNTs contained in the soot and the highest value was obtained in helium, 10 times more than in argon. Also, it was found the thermal conductivity of the carrier gas has a strong influence upon ablated mass and product deposition. The RBM and G Raman bands analysis have shown no influence of carries gas over the SWCNTs diameters distribution, respectively semiconducting character of SWCNTs, in all cases semiconducting SWCNTs being obtained. Our work concludes that helium is the best ablation gas, being 2 times more expensive than nitrogen but producing 8 times more SWCNTs.