Characterization of carbon nanotubes produced by arc discharge: Effect of the background pressure

Single walled carbon nanotubes (SWNT) produced by the anodic arc discharge over a range of constant background pressures of helium (100-1000 Torr) were examined under a high-resolution transmission electron microscope, and a Raman spectrometer. It was found that the average SWNT diameter is about 2 nm and fairly independent of the background pressure. Analysis of the relative purity of SWNTs samples suggests that highest SWNT relative concentration can be obtained at background pressure of about 200-300 Torr. Measured anode ablation rate increases linearly with background pressure. The model of the anodic arc discharge was developed. It was found that the predicted anode ablation rate agrees well with experiment suggesting that electron temperature in the anodic arc is about 0.5 eV. (C) 2004 American Institute of Physics.