SHIROMARU Haruo Tokyo Metropolitan University, Department of Chemistry, Associate Professor, 都市教養学部, 助教授 (70196632)
SUZUKI Shinzo Tokyo Metropolitan University, Department of Chemistry, Research Associate, 都市教養学部, 助手 (10226516)
KATAURA Hiromichi Nanotechnology Research Institute, Advanced Industrial Science and Technology, Group Leader, ナノテクノロジー研究部門, グループ長 (30194757)
|Budget Amount *help
¥14,300,000 (Direct Cost: ¥14,300,000)
Fiscal Year 2005: ¥6,100,000 (Direct Cost: ¥6,100,000)
Fiscal Year 2004: ¥8,200,000 (Direct Cost: ¥8,200,000)
Single wall carbon nanotubes (SWNTs), having diameters less than 1nm (almost similar to the radius of solvent-extractable fullerenes), were prepared by using Rh/Pd-carbon composite rods, with laser furnace technique in argon and nitrogen atmosphere. The following experimental findings are obtained.
1. It was found that, the diameter distribution of SWNTs obtained in nitrogen atmosphere is bi-oader (from that less than 1 nm to that larger than 1 nm), than that obtained in argon atmosphere. This tendency was confirmed by Raman spectroscopy, UV-VIS-NIR absorption spectroscopy, and fluorescence mapping measurement in NIR region for mono-dispersed SWNTs. Particularly, in nitrogen gas atmosphere, the carbon materials containing semi-conducting SWNTs, the chiral indices of those are mainly (6,5) and (5,4). Additionally it was indicated that annealing for a few tens of minutes is required, for SWNTs having diameters larger than 1nm to grow efficiently.
2. On the other hand, as for the formation process of fullerenes, it was found that there are almost no solvent-extractable or sublimable fullerenes, in the condition suitable for the formation of SWNTs.
3. In order to interpret these experimental findings, the following model is proposed. Cooling effect for carhon particles or metal particles prepared immediately after laser vaporization is stronger in nitrogen atmosphere than in argon gas atmosphere, when compared in the same inner pressure and the same ambient temperature. Therefore, if it is assumed that the time for Rh/Pd particles prepared by laser vaporization to reach to the temperature is shorter in nitrogen gas than in argon gas, where it can work as the field of SWNT formation, it is possible to consider that the precursors for fullerenes are consumed as those for SWNTs.