Nanoscale optical imaging of electronic and vibronic states in carbon nanotubes

单壁碳纳米管(SWNTs)由于其特殊的性质，最终将作为光子学、光电子学和纳米电子学的纳米级构建块发挥重要作用。然而，在实际的单壁碳纳米管中，不同类型的局域缺陷会改变所需的性质，例如激子能带态的准无限空间范围。此外，缺陷相关的陷阱态是导致单壁碳纳米管极低的光致发光量子产率的原因，这将限制其在器件中的应用。我们建议用空间分辨率为10 nm的近场光谱学来研究单根单壁碳纳米管的电子和振动性质。我们成像了特定单壁碳纳米管中光致发光激子态的空间范围，并研究了陷阱态的光谱特征以确定它们的物理起源。我们的结果将对理解局域缺陷在准无限电子系统中的作用具有重要意义。从这一点上，可以为单壁碳纳米管开发出从缺陷中受益的器件概念，比如故意掺杂的无机半导体材料。

Based on their exceptional properties, single-walled carbon nanotubes (SWNTs) will eventually play an important role as nanometer-scale building-blocks for photonics, opto- and nanoelectronics. In a real SWNT however, different types of localized defects alter the desired properties such as the quasi-infinite spatial extent of excitonic band states. Furthermore, defect related trap states are discussed to be responsible for the extremely low photoluminescence quantum yield of SWNTs which is expected to limit their applicability in devices.We propose to study the electronic and vibronic properties of single SWNTs by near-field optical spectroscopy with a spatial resolution of 10 nm. We image the spatial extent of the photoluminescent excitonic states in a given SWNT and investigate the spectroscopic signatures of trap states to identify their physical origin. Our results will be of major significance for the understanding of the role of localized defects in quasi-infinite electronic systems. From this, device concepts that benefit from defects, as in the case of intentionally doped anorganic semiconductor materials, could be developed for SWNTs.