Kavan Ladislav, Kalbac Martin, Zukalova Markéta, Dunsch Lothar
J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, Dolejskova 3, CZ-182 23 Prague 8, Czech Republic.
J Phys Chem B. 2005 Oct 27;109(42):19613-9. doi: 10.1021/jp052910e.
Raman spectra of electrochemically charged single-wall carbon nanotubes (HiPco) were studied by five different laser photon energies between 1.56 and 1.92 eV. The bands of radial breathing modes (RBM) were assigned to defined chiralities by using the experimental Kataura plot. The particular (n,m) tubes exhibit different sensitivity to electrochemical doping, monitored as the attenuation of the RBM intensities. Tubes which are in good resonance with the exciting laser exhibit strong doping-induced drop of the RBM intensity. On the other hand, tubes whose optical transition energy is larger than the energy of an exciting photon show only small changes of their RBM intensities upon doping. This rule presents a tool for analysis of mixtures of single-walled carbon tubes of unknown chiralities. It also asks for a re-interpretation of some earlier results which were reported on the diameter-selectivity of doping. The radial breathing mode in strongly n- or p-doped nanotubes exhibited a blue-shift. A suggested interpretation follows from the charging-induced structural changes of SWCNTs bundles, which also includes a partial de-bundling of tube ropes.
利用1.56至1.92电子伏特之间的五种不同激光光子能量，研究了电化学充电的单壁碳纳米管（HiPco）的拉曼光谱。通过使用实验性的片仓图，将径向呼吸模式（RBM）的能带分配给确定的手性。特定的（n,m）管对电化学掺杂表现出不同的敏感性，通过监测RBM强度的衰减来观察。与激发激光处于良好共振的管表现出强烈的掺杂诱导的RBM强度下降。另一方面，光学跃迁能量大于激发光子能量的管在掺杂时其RBM强度仅显示出微小变化。该规则为分析未知手性的单壁碳管混合物提供了一种工具。它还要求对一些早期关于掺杂直径选择性的结果进行重新解释。在强n型或p型掺杂的纳米管中，径向呼吸模式表现出蓝移。一种建议的解释源于单壁碳纳米管束的充电诱导结构变化，这也包括管绳的部分解束。
