Pressure dependence of the structures of carbonaceous deposits formed by laser ablation on targets composed of carbon, nickel, and cobalt

The structures of carbonaceous deposits obtained through laser ablations using targets composed of C, Ni, and Co under various Ar gas pressures were studied. The pressure dependence of the target's surface morphology and the structure was also studied. When the pressure was 100 Torr or below, only carbon was evaporated from the target and amorphous carbon was formed during the laser ablation. When the pressure was 200 Torr or higher, both carbon and metal was evaporated and single-wall carbon nanotubes and amorphous carbon were formed during the laser ablation. A mechanism of the single-wall carbon nanotube formation by laser ablation is proposed.