An atlas of carbon nanotube optical transitions
An atlas of carbon nanotube optical transitions
复制标题
碳纳米管光学跃迁图集
DOI：
10.1038/nnano.2012.52
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发表时间：
2012-05-01
影响因子：
38.3
通讯作者：
Wang, Feng
中科院分区：
文献类型：
--
作者：
Liu, Kaihui;Deslippe, Jack;Wang, Feng
电子-电子相互作用在一维系统中显著增强(1)，单壁碳纳米管为一维研究这种相互作用和相关的多体效应提供了独特的机会（2-4）。然而，单壁纳米管可以有很宽的直径范围和数百种不同的结构，每种结构都由其手性指数（n,m）（5,6）来定义，其中n和m是整数，可以有从0到30或更大的值。此外，这些结构中有三分之一是金属，三分之二是半导体，它们在许多不同的频率上显示光学共振。因此，对纳米管中多体效应的系统研究将受益于一种基于测量其光学共振来识别纳米管手性指数的技术，反之亦然。在这里，我们报告了基于206种不同单壁纳米管结构的手性指数的电子衍射测量和光学共振的瑞利散射测量（7,8），建立了纳米管光学跃迁的结构-性质“图谱”。纳米管悬浮在硅衬底上的开缝结构上，直径在1.3-4.7 nm之间。我们也使用该图谱作为系统研究单壁纳米管激发态多体效应的起点（9-16）。我们发现，电子-电子相互作用使金属纳米管和半导体纳米管的光学共振能发生相同量的位移，并且这种位移（对应于有效费米速度重整化）随着纳米管直径的增加而单调增加。这种行为源于两个来源：一个有趣的远程电子-电子相互作用效应的抵消，以及短程电子-电子相互作用对直径的依赖（10,11）。
Electron-electron interactions are significantly enhanced in one-dimensional systems(1), and single-walled carbon nanotubes provide a unique opportunity for studying such interactions and the related many-body effects in one dimension(2-4). However, single-walled nanotubes can have a wide range of diameters and hundreds of different structures, each defined by its chiral index (n,m)(5,6), where n and m are integers that can have values from zero up to 30 or more. Moreover, one-third of these structures are metals and two-thirds are semiconductors, and they display optical resonances at many different frequencies. Systematic studies of many-body effects in nanotubes would therefore benefit from the availability of a technique for identifying the chiral index of a nanotube based on a measurement of its optical resonances, and vice versa. Here, we report the establishment of a structure-property 'atlas' for nanotube optical transitions based on simultaneous electron diffraction measurements of the chiral index and Rayleigh scattering measurements of the optical resonances(7,8) of 206 different single-walled nanotube structures. The nanotubes, which were suspended across open slit structures on silicon substrates, had diameters in the range 1.3-4.7 nm. We also use this atlas as a starting point for a systematic study of many-body effects in the excited states of single-walled nanotubes(9-16). We find that electron-electron interactions shift the optical resonance energies by the same amount for both metallic and semiconducting nanotubes, and that this shift (which corresponds to an effective Fermi velocity renormalization) increases monotonically with nanotube diameter. This behaviour arises from two sources: an intriguing cancellation of long-range electron-electron interaction effects, and the dependence of short-range electronelectron interactions on diameter(10,11).