| Project/Area Number |
11165231
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| Research Category |
Grant-in-Aid for Scientific Research on Priority Areas (A)
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| Allocation Type | Single-year Grants |
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| Research Institution | TOKYO METROPOLITAN UNIVERSITY |
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Principal Investigator |
KATAURA Hiromichi Graduate School of Science, Dept of Physics, TOKYO METROPOLITAN UNIVERSITY, Assistant Professor, 理学研究科, 助手 (30194757)
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| Project Period (FY) |
1999 – 2000
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| Project Status |
Completed (Fiscal Year 2000)
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| Budget Amount *help |
¥15,900,000 (Direct Cost: ¥15,900,000)
Fiscal Year 2000: ¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1999: ¥13,900,000 (Direct Cost: ¥13,900,000)
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| Keywords | nanotube / carbon / Raman scattering / Optical absorption / Synthesis / Purification / 単層ナノチューブ / 光物性 / スペクトロスコピー / 電子構造 |
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| Research Abstract |
To see differences on the electronic and vibrational properties of single-wall carbon nanotubes (SWNTs) between isolated tubes and thick bundles, we prepared variety samples in bundle thickness by purification and doping-dedoping methods, and then measured resonance Raman spectra. We found that several tens nm thick bundles show 5% up-shift of radial breathing mode frequency as predicted by theoretical works. On the other hand, breathing mode frequency observed in multi-wall carbon nanotubes show further up-shifts. It was indicated that the stronger inter-layer interaction leads to higher breathing mode frequency. While no significant modulation was observed in electronic structure of nanotubes by changing bundle thickness, optical transition shows slight broadening and downshifts. This is a typical feature of molecular solids. Since the pristine sample is a mixture of isolated tubes and bundles, breathing mode Raman peak shows oscillation by changing excitation wavelength as results of combined effects mentioned above. This oscillation pretends to be many kinds of nanotubes are on resonance. In other words, we found that sorts of nanotubes are limited observed in Raman spectra.
We did fullerene doping inside SWNTs. We found that SWNTs encapsulating fullerenes can be synthesized in high-yield when we tuned the diameter distribution to be centered at 1.37 nm. Since the yield is sufficiently high, this kind of material should be regarded as a new solid phase of carbon, as theoretical calculation indicates considerable hybridization between C_<60> and nanotube and large down shift of LUMO band of C_<60>. Electron microscopy, X ray. diffraction, and Raman scattering reveal that our sample is encapsulating fullerenes with filling factor 60 - 70 %. Interestingly, It wa found that C_<60> spontaneously forms dimers and changes to one-dimensional polymer by laser irradiation or potassium doping.
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