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Laser Ablation of Graphite−Co/Ni and Growth of Single-Wall Carbon Nanotubes in Vortexes Formed in an Ar Atmosphere

2000; American Chemical Society; Volume: 104; Issue: 29 Linguagem: Inglês

10.1021/jp000359+

1520-6106

F. Kokai, Kunimitsu Takahashi, Masako Yudasaka, Sumio Iijima,

Laser-Ablation Synthesis of Nanoparticles

To study the Nd:YAG laser ablation of graphite−Co/Ni (1.2 at. %) and the growth of single-wall carbon nanotubes (SWNTs) in an Ar atmosphere at 1200 °C, we applied time-resolved imaging and spectroscopic techniques. These techniques are based on measuring the laser plume emission and light scattering of growing materials. Laser ablation was performed at a fluence of 1.7 J/cm2 at 1200 °C and at room temperature for comparison. At 1200 °C, we observed temporally and spatially dependent emissions of C, C2, Co, Ni, and Ar species. In addition, emission, probably due to hot clusters and/or particles grown through the interaction with Ar atoms, could be seen at up to 1.5 ms. This emission showed the images separating into two regions at >100 μs, resulting from the formation of vortexes. In the light scattering images at 2−1000 ms after 1200 °C ablation, we observed the vortexes propagating forward (about 7 cm from the target) during 200 ms and then flowing downward to the target. We suggest that the time availab...