Excitation loss spectra of finite carbon nanotubes

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• 作者：R.B. Chen
• 关键词：Carbon nanotubes ; Optical properties
• 刊名：Physica E
• 出版年：2008
• 出版时间：March 2008
• 年：2008
• 卷：40
• 期：5
• 页码：1407-1409
• 全文大小：234 K

文摘

The sp³ and 2p_z tight-binding models are, respectively, used to calculate electronic states. The static dielectric function is evaluated from the gradient approximation. Electronic states have differences within the sp³ and the 2p_z tight-binding models. The former (latter) exhibits asymmetric (symmetric) energy dispersions about Fermi level with an angular momentum. The imaginary and the real parts of the dielectric function, respectively, exhibit the special peaks and dips. The prominent π and π+σ plasmon peaks exist at ω<4γ₀ and ω>4γ₀ (γ₀ is the nearest-neighbor overlap integral), respectively. Prominent peak energies are almost independent of length for sufficiently long carbon nanotubes (CNTs). These results illustrate the quasi-zero-dimensional character. Moreover, for different nanotube lengths, they reveal a common feature—prominent plasmon structures at and . This result follows the fact that all CNTs are derived their states from those of a graphene sheet. On the other hand, for cdca24e41c108f975ae2382"" title=""Click to view the MathML source"" alt=""Click to view the MathML source"">ω<2γ₀ the prominent peaks of the finite CNTs are associated with the standing waves. The predicted loss spectra could be verified by electron energy loss spectra (EELS).