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大布口袋

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[资源] 最新NanoLetter石墨烯变单原子碳链并TEM内原位测导电特性by Benhart Group

最近几年，石墨烯吸引了全世界广大科研工作者的兴趣，它不仅是已知材料中最薄的一种，还非常牢固坚硬；作为单质，它在室温下传递电子的速度比已知导体都快。石墨烯开创了二维纳米片层材料的新领域，而本次Benhart课题组，在石墨烯的基础上，利用原位STM（scanning tunneling microscopy）及TEM（transmission electron microscopy）技术，获得了的单原子碳链结构，并实现其电导特性的测试。单原子碳链的电导性能（实验）与其理论未受到应力作用的碳链模拟值相比低很多，随后的first-principles density functional theory (DFT)及many-body perturbation theory (MBPT)计算也提供了相应依据，这篇文章为最小一维导电材料的研究提供了新的方向。

Electrical Transport Measured in Atomic Carbon Chains

ABSTRACT: The first electrical-transport measurements of monatomic carbon chains are reported in this study. The chains were obtained by unraveling carbon atoms from graphene ribbons while an electrical current flowed through the ribbon and, successively, through the chain. The formation of the chains was accompanied by a characteristic drop in the electrical conductivity.
The conductivity of the chains was much lower than previously predicted for ideal chains. First-principles calculations using both density functional and many-body perturbation theory show that strain in the chains has an increasing effect on the conductivity as the length of the chains increases. Indeed, carbon chains are always under varying nonzero strain that transforms their atomic structure from the cumulene to the polyyne configuration, thus inducing a tunable band gap. The modified electronic structure and the characteristics of the contact to the graphitic periphery explain the low conductivity of the locally constrained carbon chain.

KEYWORDS: Atomic carbon chains, atomic wires, carbynes, electron microscopy, quantum transport[ Last edited by 大布口袋 on 2013-8-2 at 17:09 ]

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