Asymmetry of resonance Raman profiles in semiconducting single-walled carbon nanotubes at the first excitonic transition
Asymmetry of resonance Raman profiles in semiconducting single-walled carbon nanotubes at the first excitonic transition
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DOI：
10.1103/physrevb.99.045404
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发表时间：
2019-01-03
影响因子：
3.7
通讯作者：
Reich, Stephanie
中科院分区：
文献类型：
--
作者：
Gordeev, Georgy;Flavel, Benjamin;Reich, Stephanie
碳纳米管是一维纳米尺度的系统，具有强烈的手性依赖的光学性质与多激子跃迁。利用共振拉曼光谱研究了不同手性的半导体单壁纳米管在第一激子跃迁时的高能G模。G模式强度对激发能的依赖性产生了与我们报道的第二激子跃迁相似的非对称共振拉曼谱。我们发现散射效率是最强的传入拉曼共振。尽管如此，第一和第二跃迁的不对称程度是不同的，并且第一跃迁分布由于较长的激子寿命而提供较窄的线形。与第二次跃迁相比，在第一次激子跃迁时的总散射效率高达25倍。五阶微扰理论，实现激子状态之间的声子散射路径，很好地再现实验数据。
Carbon nanotubes are one-dimensional nanoscale systems with strongly pronounced chirality-dependent optical properties with multiple excitonic transitions. We investigate the high-energy G mode of semiconducting single-walled nanotubes of different chiralities at first excitonic transition by applying resonant Raman spectroscopy. The G mode intensity dependence on excitation energy yielded asymmetric resonance Raman profiles similar to ones we reported for the second excitonic transition. We find the scattering efficiency to be strongest at the incoming Raman resonance. Still, the degree of asymmetry is different for the first and second transitions and the first transition profiles provide a narrower line shape due to longer exciton lifetimes. The overall scattering efficiency is up to a factor of 25 times more intense at first excitonic transition, compared to the second transition. The fifth-order perturbation theory, with implemented phonon scattering pathways between excitonic states, excellently reproduced experimental data.