In 1995, Smalley and co-workers produced carbon nanotubes using laser ablation technique . In the laser ablation technique, a high power laser was used to vaporize carbon from a graphite target at high temperature. Both MWNTs and SWNTs can be produced with this technique. In order to generate SWNTs, metal particles as catalysts must be added to the graphite targets similar to the arc discharge technique. The quantity and quality of produced carbon nanotubes depend on several factors such as the amount and type of catalysts, laser power and wavelength, temperature, pressure, type of inert gas, and the fluid dynamics near the carbon target. Schematic diagram of the laser ablation apparatus was shown in Fig. 1. The laser is focused onto a carbon targets containing 1.2 % of cobalt/nickel with 98.8 % of graphite composite that is placed in a 1200°C quartz tube furnace under the argon atmosphere (~500 Torr). These conditions were achieved for production of SWNTs in 1996 by Smalley’s group . In such technique, argon gas carries the vapors from the high temperature chamber into a cooled collector positioned downstream. The nanotubes will self-assemble from carbon vapors and condense on the walls of the flow tube. The diameter distribution of SWNTs from this method varies about 1.0 - 1.6 nm. Carbon nanotubes produced by laser ablation were purer (up to 90 % purity) than those produced in the arc discharge process and have a very narrow distribution of diameters.
Fig. 1 Schematic diagram of the laser ablation apparatus.
1. T. Guo, P. Nikolaev, A. Thess, D.T. Colbert and R.E. Smalley, Catalytic growth of single-walled nanotubes by laser vaporization, Chem. Phys. Lett., 1995, 243, 49-54.
2. A. Thess, R. Lee, P. Nikolaev, H. Dai, P. Petit, J. Robert, C. Xu, Y.H. Lee, S.G. Kim, A.G. Rinzler, D.T. Colbert, G.E. Scuseria, D. Tománek, J.E. Fischer, and R.E. Smalley, Crystalline ropes of metallic carbon nanotubes, Science, 1996, 273, 483–487.