Single-walled carbon nanotubes (SWNTs) with a narrow diameter distribution have been synthesized by hot-filament chemical vapor deposition using acetylene at 590 degrees C. Iron nanoparticles with diameters of 1.6, 2.0, 2.5, 5.0 and 10 nm (standard deviation: approximate to 10%) obtained with a differential mobility analyzer were used as a catalyst without any supporting materials on a substrate. SWNTs were obtained from 2.0 inn or smaller particles. The ratio of G band to D band in Raman spectra was as high as 35 without purification. indicating that high-quality SWNTs were synthesized. The SWNT diameters correlated with the particle diameters. demonstrating diameter-controlled SWNT growth. (c) 2006 Elsevier B.V. All rights reserved.