Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
Phys Rev Lett. 2011 Dec 16;107(25):257402. doi: 10.1103/PhysRevLett.107.257402.
We present evidence for the generation of free carriers in aggregated single-wall carbon nanotubes by photoexcitation in the energetic range of the π→π(*) transition associated with the M saddle point of the graphene lattice. The underlying broad absorption culminating at 4.3 eV can be fit well with a Fano line shape that describes strong coupling of a saddle-point exciton to an underlying free electron-hole pair continuum. Moreover, it is demonstrated that transitions in this energetic region autoionize into the continuum by detecting features unique to the presence of free charges in the transient transmission spectra of the continuum-embedded second sub-band exciton, S(2).
我们通过在与石墨烯晶格 M 鞍点相关的π→π(*)跃迁的能量范围内的光激发，证明了在聚集的单壁碳纳米管中产生自由载流子。在 4.3 eV 处达到峰值的宽吸收带可以很好地与描述鞍点激子与基础自由电子-空穴对连续体强烈耦合的 Fano 线形状相吻合。此外，通过检测嵌入连续体的第二子带激子 S(2)的瞬态传输光谱中自由电荷存在的独特特征，证明了该能量区域中的跃迁通过自电离进入连续体。
