Growth of single-wall carbon nanotubes dependent on laser power density and ambient gas pressure during room-temperature CO2 laser vaporization |
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Authors: | F. Kokai K. Takahashi D. Kasuya M. Yudasaka S. Iijima |
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Affiliation: | (1) Institute of Research and Innovation, 1201 Takada, Kashiwa, Chiba 277-0861, Japan, JP;(2) Department of Physics, Meijo University, Tenpaku-ku, Nagoya 468-8502, Japan, JP;(3) JST-ICORP Nanotubelites Project, c/o NEC Corporation, 34 Miyukigaoka, Tsukuba, Ibaraki 305-8601, Japan, JP;(4) NEC Corporation, 34 Miyukigaoka, Tsukuba, Ibaraki 305-8601, Japan, JP |
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Abstract: | Single-wall carbon nanotubes (SWNTs) were synthesized by the irradiation of 20-ms CO2 laser pulses onto a graphite–Co/Ni target at room temperature. We investigated the effect of laser power density (10–150 kW/cm2) and ambient Ar gas pressure (150–760 Torr) on the abundance of SWNTs with lengths of up to about 200 nm in soot-like carbonaceous deposits. For a constant power density (30 kW/cm2), depending on the Ar gas pressure, SWNTs with diameters of 1.2–1.4 nm were synthesized. Expansion behavior and temperature-fall rates of clusters and/or particles in laser plumes were also analyzed by high-speed video imaging and temporally and spatially resolved emission spectroscopy. The temperature-fall rates were estimated to be 171–427 K/ms. The SWNT growth on the time scale of a few milliseconds appeared to be related to some features of condensing clusters and/or particles, including resident densities, collision frequencies and temperatures. Received: 16 July 2001 / Accepted: 23 July 2001 / Published online: 30 August 2001 |
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Keywords: | PACS: 81.05.Tp 81.15.Fg 61.46.+w |
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