Investigating the formation of single-wail carbon nanotubes (SWNTs) from a target composed of graphite, Ni, and Co, we compared the use of a pulsed CO2 laser (pulse width of 20 ms, laser-power density of 0.1 MW/cm(2)) with the use of a pulsed Nd:YAC laser (pulse width of 5-7 ns, laser-power density of 4 GW/cm(2)). When the total irradiation energy was 2 kW/cm(2) for the CO2 laser ablation and 2.4 kW/cm(2) for the Nd:YAC laser ablation, SWNTs could be formed at 300 K by CO2 laser ablation, whereas the lowest temperature at which they could be formed by Nd:YAG laser ablation was about 1170 K. The lowest pressure allowing SWNT formation was 50 Torr for CO2 laser ablation and 200 Torr for Nd:YAG laser ablation. The structures of carbonaceous deposits and of the target surfaces indicated that CO2 laser ablation resulted in carbon being emitted from the edges of or defects in the graphite particles and most of the Ni and Co being emitted from the target. Pulsed Nd:YAG laser ablation, on the other hand, has been reported to result in graphite melting and mixing with Ni and Co on the target surface, the mixture being expelled from the target surface, and clumps of Ni and Co remaining on the target surface after the laser ablation, We think these differences are due to the different laser-power densities and pulse widths.