Transient Absorption Spectroscopy of Excitons in an Individual Suspended Metallic Carbon Nanotube
Transient Absorption Spectroscopy of Excitons in an Individual Suspended Metallic Carbon Nanotube
复制标题
单个悬浮金属碳纳米管中激子的瞬态吸收光谱
DOI：
10.1021/jz401497n
复制
发表时间：
2013-09-19
影响因子：
5.7
通讯作者：
Huang, Libai
中科院分区：
文献类型：
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作者：
Gao, Bo;Hartland, Gregory V.;Huang, Libai
我们提出了单个金属单壁碳纳米管（SWNTs）的飞秒瞬态吸收测量，以阐明环境对其光谱和动力学的影响。利用原子力显微镜对分离的悬浮纳米管进行了定位，并利用拉曼光谱测定了所选纳米管的手性指数。通过记录不同探针波长的瞬态吸收图像，获得了单壁碳纳米管的瞬态吸收光谱。这种独特的实验方法消除了这些复杂材料的超快测量中的样品异质性，并提供了一种直接的方法来揭示衬底的作用。结果表明，最低激子跃迁的红移为~ 40 meV，这是由于衬底的介电屏蔽效应。在单个金属纳米管中观察到能量弛豫，衰减常数为几百fs，衰减常数约为10 ps。我们将快慢衰减组分归因于光学声子和声子的载流子散射。
We present femtosecond transient absorption measurements of individual metallic single-wall carbon nanotubes (SWNTs) to elucidate environmental effects on their spectroscopy and dynamics. Isolated suspended SWNTs were located using atomic force microscopy, and Raman spectroscopy was employed to determine the chiral index of select nanotubes. Transient absorption spectra of the SWNTs were obtained by recording transient absorption images at different probe wavelengths. This unique experimental approach removes sample heterogeneity in ultrafast measurements of these complex materials and provides a direct means to unravel the role of the substrate. The results show a ∼40 meV red shift of the lowest exciton transition, which is attributed to dielectric screening effects by the substrate. Energy relaxation in individual metallic nanotubes was observed with decay constants of a few hundred fs and about 10 ps. We attributed the fast and slow decay components to carrier scattering by optical and acoustic phonons...