Gas-dynamic consideration of the laser evaporation synthesis of single-wall carbon nanotubes

The abundance of carbon single-wall nanotubes (SWNTs) in soot synthesized b y pulsed laser evaporation of graphite is studied over a wide range of synt hesis conditions. The derived SWNT growth time-scale appears to be much lon ger than any characteristic time-scale in a simplified model of the relaxat ion of a high-pressure hot condensing gas bubble in a background atmosphere . It is concluded that SWNT nucleation and growth take place in relaxed, co ndensed, thermalized evaporation products at an optimal temperature between 850-1250 degrees C at a rate of few mu m length per second, which is consi stent with a condensed state "precipitation" mechanism for the SWNT formati on.