Ultrafast dynamics in metallic and semiconducting carbon nanotubes
Ultrafast dynamics in metallic and semiconducting carbon nanotubes
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DOI：
10.1103/physrevb.80.205411
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发表时间：
2009-11-01
影响因子：
3.7
通讯作者：
Vardeny, Z. Valy
中科院分区：
文献类型：
--
作者：
Luer, Larry;Lanzani, Guglielmo;Vardeny, Z. Valy
结合几种超快激光系统，测量了在1.6 eV脉冲光激励下，在从中红外到可见光的很宽的探测光谱范围内，具有金属和半导体性质的手性富碳纳米管团簇中偏振的泵浦/探测传输的瞬时变化。我们发现了一个类似于0.7 eV的光致吸收带，这是由于金属管中热的狄拉克费米子引起的，并测量了它的动力学。热载流子在电子系统内的平衡时间类似于400fs，与晶格的平衡时间类似于2ps；这与热狄拉克费米子在石墨烯中的热化作用相一致。我们还指定了半导体管中的激子跃迁，主要是(6，5)手性的激子跃迁；特别是，类似于0.4 eV的激子内跃迁代表激子结合能的下限。
Transient polarized pump/probe transmission changes upon pulse photoexcitation at 1.6 eV were measured in chiral enriched carbon nanotubes ensembles of both metallic and semiconductor characters, in a very broad probe spectral range from mid-IR to visible, combining several ultrafast laser systems. We identify a photoinduced absorption band at similar to 0.7 eV as due to hot Dirac fermions in the metallic tubes and measure its dynamics. The hot carriers equilibrate within the electronic system in similar to 400 fs and with the lattice within similar to 2 ps; in agreement with hot Dirac fermions thermalization in graphene. We also assign excitonic transitions in the semiconducting tubes, mainly of (6,5) chirality; in particular, an intraexciton transition at similar to 0.4 eV represents a lower limit for the exciton binding energy.