Turning Peapods into Double-Walled Carbon Nanotubes
Turning Peapods into Double-Walled Carbon Nanotubes
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DOI：
10.1557/mrs2004.77
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发表时间：
2004-04
期刊：
影响因子：
5
通讯作者：
S. Bandow;K. Hirahara;T. Hiraoka;Gugang Chen;P. Eklund;S. Iijima
中科院分区：
文献类型：
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作者：
S. Bandow;K. Hirahara;T. Hiraoka;Gugang Chen;P. Eklund;S. Iijima
介绍了单壁碳纳米管（豆荚）包裹C_60制备双壁碳纳米管（DWNTs）的途径。一维排列的C_（60）分子在纳米管中逐渐聚结，并形成C_（60）二聚体、三聚体、四聚体等中间体。除了在纳米管空间中可视化的这些有趣的结构转变之外，纳米管本身非常稳定，当使用纳米管内部作为反应场或分子存储空间时，这种结构稳定性非常重要。在光吸收方面，DWNTs的最低能量吸收带（~0.65 eV）较SWNTs具有展宽和下移的特征，我们期望DWNTs的这种光吸收特性将有助于其在光纤通信吸收器件中的应用。拉曼实验给出了直径小于~ 1 nm的纳米管的C-C伸缩模振动频率的新信息，其显示振动频率随着管直径的减小而减小。这种直径依赖性可以通过C-C相互作用中sp3特征的混合物来解释。因此，直径>1 nm的纳米管的电子和机械性质预计将不同于直径约1 nm的纳米管，我们预计在小直径管中会出现新的现象。
The formation pathway to double-walled carbon nanotubes (DWNTs) from C_60 encased within single-walled carbon nanotubes (peapods) is introduced in this article. Onedimensionally arranged C_60 molecules coalesce gradually within the nanotube and change the structure to C_60 dimers, trimers, tetramers, and so on as intermediates. In addition to these interesting structural transformations visualized in the nanotube space, the nanotube itself is very stable, and this structural stability is very important when using the interior of the nanotube as the reaction field or the space for molecular storage. In terms of optical absorption, the lowest energy absorption band for DWNTs, ~0.65 eV, shows broadened and downshifted features as compared with that of SWNTs.We expect that this opticalabsorption feature will lead to the use of DWNTs in absorbing devices for optical-fiber communications. The Raman experiments give new information about the frequency of the C–C stretching-mode vibration for nanotubes with diameters of less than ~ 1 nm, which shows a decrease in vibration frequency with decreasing tube diameter. This diameter dependence can be explauned by an admixture of sp3 character in the C–C interaction. Therefore, the electronic and mechanical properties of nanotubes with diameters of >1 nm are expected to be different from nanotubes of the ~1-nm-diameter class, and we anticipate that new phenomena will occur in small-diameter tubes.