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【科研新闻】碳纳米管在真空条件下是极佳导体和红外热探测器
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研究发现碳纳米管在真空条件下是极佳导体和红外热探测器: Researchers at the University of California, Riverside have shown for the first time that carbon nanotubes in a vacuum show excellent conductivity and can be very effective infrared detectors because of their high sensitivity to light. The findings are published in a paper titled Bolometric Infrared Photoresponse of Suspended Single-Walled Carbon Nanotube Films, in today’s edition of the journal Science, co-authored by UCR researchers Mikhail Itkis, Ferenc Borondics and Aiping Yu, and led by Distinguished Professor of Chemistry and Chemical and Environmental Engineering Robert Haddon. The research was conducted at the Center for Nanoscale Science and Engineering which is a part of the College of Natural and Agricultural Sciences and the Bourns College of Engineering at UCR. “What you have is a substance that is very efficient at collecting light and converting that energy to heat,” Haddon said. “You have a material that is really well designed to function as an infrared detecting device.” The findings could be of great interest to the military and law enforcement which often need to use infrared detection technology to look for people and vehicles in nighttime situations. For scientist, the discovery could be beneficial for infrared spectrometry and astronomy. The UCR findings contradict previous studies of the photoconductivity of carbon nanotubes, which showed that when irradiated with light, carbon nanotubes had a weak response, suggesting low photoconductivity. However, those previous experiments placed the carbon nanotubes on a substrate that acted to dissipate much of the heat built up by irradiation, Haddon said. The UCR experiment placed a .5 millimeter strip of purified carbon nanotubes that were suspended across two electrodes in a vacuum, with no substrate to dissipate the heat. The results generated anywhere from five to 10 orders of magnitude (105 - 106), of the amount of heat found in previous tests. “We think this is due in large part to the lack of a substrate, which works like a heat sink to absorb much of the heat buildup,” Haddon added. Placing the nanotube strip in a vacuum also eliminates heat loss via the air. 来源:http://www.azonano.com/news.asp?newsID=2186 [ Last edited by mainpro on 2006-4-26 at 23:26 ] |
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westwolf
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不错,楼主的东西在这里,希望楼主能加以简要的介绍和文章的去处更好些,不论怎么样感谢提供信息. Science 21 April 2006: Vol. 312. no. 5772, pp. 413 - 416 DOI: 10.1126/science.1125695 Reports Bolometric Infrared Photoresponse of Suspended Single-Walled Carbon Nanotube Films Mikhail E. Itkis, Ferenc Borondics,* Aiping Yu, Robert C. Haddon{dagger} The photoresponse in the electrical conductivity of a single-walled carbon nanotube (SWNT) film is dramatically enhanced when the nanotube film is suspended in vacuum. We show here that the change in conductivity is bolometric (caused by heating of the SWNT network). Electron-phonon interactions lead to ultrafast relaxation of the photoexcited carriers, and the energy of the incident infrared (IR) radiation is efficiently transferred to the crystal lattice. It is not the presence of photoexcited holes and electrons, but a rise in temperature, that results in a change in resistance; thus, photoconductivity experiments cannot be used to support the band picture over the exciton model of excited states in carbon nanotubes. The photoresponse of suspended SWNT films is sufficiently high that they may function as the sensitive element of an IR bolometric detector. Center for Nanoscale Science and Engineering, Departments of Chemistry and Chemical and Environmental Engineering, University of California, Riverside, CA 92521–0403, USA. * Present address: Magyar Tudományos Akadémia, Szliárdtestfizikai és Optikai Kutatóintézete, Budapest, H 1525, Hungary. To whom correspondence should be addressed. E-mail: haddon@ucr.edu   |
2楼2006-04-27 00:45:34
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3楼2006-04-27 02:46:21