Phonon dephasing and population decay dynamics of the G-band of semiconducting single-wall carbon nanotubes
Phonon dephasing and population decay dynamics of the G-band of semiconducting single-wall carbon nanotubes
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DOI：
10.1103/physrevb.82.165432
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发表时间：
2010-10-19
影响因子：
3.7
通讯作者：
Cicerone, Marcus T.
中科院分区：
文献类型：
--
作者：
Lee, Young Jong;Parekh, Sapun H.;Cicerone, Marcus T.
利用宽带时间分辨相干反斯托克斯拉曼散射和时间分辨非相干反斯托克斯拉曼散射研究了半导体单壁碳纳米管(SWCNTs)光学声子的退相和布居衰减动力学。通过简单地调整连续谱脉冲的光谱带宽，我们能够在同一样品中连续地直接测量G带的总退相时间T(2)和布居衰减时间T(1)，这使得人们可以排除由于不同样品条件和不同测量方案所测量的动态值的比较而产生的伪影。给出了两种不同的单壁碳纳米管样品的T(1)和T(2)/2的值：玻璃薄膜中的束状样品和水中分散的样品。虽然两个样品的T(1)值相似，但由T(2)/2和T(1)测量得到的纯退相时间T*(2)/2在束状单壁碳纳米管中比在孤立分散中更快。这表明薄膜中相邻的管子对振动模的扰动比周围的表面活性剂更强烈，纯退相动力学对微扰更敏感。
The dephasing and population decay dynamics of optical phonons are studied for semiconducting single-wall carbon nanotubes (SWCNTs) using broadband time-resolved coherent anti-Stokes Raman scattering and time-resolved incoherent anti-Stokes Raman scattering. By simply adjusting the spectral bandwidth of a continuum pulse, we are able to directly measure both the total dephasing time, T(2), and the population decay time, T(1), of the G-band sequentially in the same sample, which allows for one to exclude artifacts due to comparison of dynamics values measured with different sample conditions and different measurement schemes. The values of T(1) and T(2)/2 are presented for two different SWCNT samples: bundles in a film on glass and a dispersion in water. While the measured T(1) values are similar for the two samples, the pure dephasing times, T*(2)/2, determined from the T(2)/2 and T(1) measurements are faster in bundled SWCNTs than in isolated dispersion. This suggests that neighboring tubes in the film perturbs the vibrational mode more strongly than surrounding surfactants and that the pure dephasing dynamics is more sensitive to the perturbation.