| Abstract
| - To increase the practical daily capacity to produce single-wall carbon nanohorns (SWNHs) with high purityby CO2 laser ablation of graphite, we made a new three-chamber system composed of a target reservoir, alaser ablation chamber, and a collection chamber. The frequency of exchanging targets was reduced byincreasing the target size (diameter, 10 cm; length, 50 cm), and the time taken to exchange targets was reducedby adding an automated exchange mechanism. Most of the SWNHs produced in the laser ablation chamberwere immediately swept into the collection chamber by an Ar gas carrier. This avoided the problem of fluffySWNHs blocking the laser beam irradiating the target and enabled the CO2 laser to be operated continuously.The resulting SWNHs had a purity of 92−95% under the optimized conditions of laser power density (15−30 kW/cm2) and target rotation speed (1−3 rpm). This increase in purity represents a remarkable improvementon the previous level of 85−90%. A practical production capacity of 1 kg/day was achieved, which is about100 times greater than the daily capacity attained by the previous single-chamber system.
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