| Project/Area Number |
10640313
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
固体物性Ⅰ(光物性・半導体・誘電体)
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| Research Institution | TOKYO METOROPOLITAN UNIVERSITY |
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Principal Investigator |
KATAURA Hiromichi TOKYO METROPOLITAN UNIVERSITY FAC OF SCIENCE, RESEARCH ASSOCIATE, 理学研究科, 助手 (30194757)
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| Project Period (FY) |
1998 – 1999
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| Project Status |
Completed (Fiscal Year 1999)
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| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 1999: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1998: ¥3,000,000 (Direct Cost: ¥3,000,000)
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| Keywords | CARBON NANOTUBE / RAMAN SCATTERING / ELECTRONIC STATES / RESONANCE RAMAN SCATTERING / 単層 / 光吸収 |
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| Research Abstract |
We have measured optical absorption spectra and resonance Raman spectra for various kinds of single-wall carbon nanotubes (SWNTs) with different diameter distributions fabricated by the laser-furnace and carbon arc methods using NiCo, Ni, RhPd, RhPt, NiY catalysts. We developed a "splay method" to make SWNT thin film and measured the optical absorption. We found three absorption bands from near infrared to visible which are reflecting π -> πィイD1*ィエD1 transitions between spike-like density of states originating from the one-dimensional van Hove singularities. The absorption structures changes with changing the diameter of the SWNT. It was found that the first and the second absorption peaks correspond to the optical transitions of semiconductors and the third one the metallic SWNTs. Raman spectrum taken with the laser excitation at the absorption band of metallic SWNTs shows a Fano line shape which is characteristics of metallic materials. Thus, we named the third absorption band as "metallic window".
Most of synthesis methods provide "bundles" of SWNTs. Thus, it is very important to investigate the effect of the bundle. It is expected that the doped bromine molecules can be removed by the evacuation if the molecules located around isolated SWNTs while the molecules inside SWNTs bundles cannot be removed. Using this doping-dedoping technique, we have measured resonance Raman scattering of isolated SWNTs. We found that the isolated metallic SWNTs do not show Fano line shape anymore. This indicates clearly that the Fano interference is intrinsic to the metallic SWNT "bundles". Further, we found that highly purified SWNTs samples show very thick bundle structures. We have measured the resonance Raman scattering of the purified samples and found that the radial breathing modes show large up-shifts which is predicted by theoretical calculation about Van der Waals interactions between SWNTs.
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