Absorption spectroscopy of individual single-walled carbon nanotubes
Absorption spectroscopy of individual single-walled carbon nanotubes
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DOI：
10.1021/nl062933k
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发表时间：
2007-05-01
期刊：
影响因子：
10.8
通讯作者：
Lounis, Brahim
中科院分区：
文献类型：
--
作者：
Berciaud, Stephane;Cognet, Laurent;Lounis, Brahim
目前生产单壁碳纳米管(SWNTs)的方法导致了含有不同长度和缺陷的金属和半导体物种混合物的异质样品。因此，单纳米管水平的光学检测应该提供检查这些异质性的可能性，前提是两种单壁碳纳米管都被同样好地检测到。在这里，我们使用光热外差探测来记录单个单壁碳纳米管的吸收图像和光谱。由于这种光热方法只依赖于光的吸收，它很容易检测到金属纳米管以及发射半导体的物种。研究了单根半导体纳米管的第一和第二光学跃迁。对最低能级光学跃迁的发射光谱和吸收光谱的比较表明，主要是较小的斯托克斯位移。观察到了近红外吸收光谱中的边带，并将其归属为激子-声子束缚态。在金属纳米管的最低跃迁附近没有检测到这样的边带。
Current methods for producing single-walled carbon nanotubes (SWNTs) lead to heterogeneous samples containing mixtures of metallic and semiconducting species with a variety of lengths and defects. Optical detection at the single nanotube level should thus offer the possibility to examine these heterogeneities provided that both SWNT species are equally well detected. Here, we used photothermal heterodyne detection to record absorption images and spectra of individual SWNTs. Because this photothermal method relies only on light absorption, it readily detects metallic nanotubes as well as the emissive semiconducting species. The first and second optical transitions in individual semicontucting nanotubes have been probed. Comparison between the emission and absorption spectra of the lowest-lying optical transition reveal mainly small Stokes shifts. Side bands in the near-infrared absorption spectra are observed and assigned to exciton-phonon bound states. No such sidebands are detected around the lowest transition of metallic nanotubes.