arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1409.3441cond-mat.mes-hall
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碳纳米管中的普适非共振吸收

Universal non-resonant absorption in carbon nanotubes

Fabien Vialla, Ermin Malic, Benjamin Langlois, Yannick Chassagneux, Carole Diederichs, Emmanuelle Deleporte, Philippe Roussignol, Jean-Sébastien Lauret, Christophe Voisin

摘要:

在半导体碳纳米管的光致发光激发测量显示了系统的非共振之间的公知的激子共振的贡献。使用全局分析方法,我们能够描绘每个手性物种的贡献,包括其微小的非共振成分。通过与最近报道的激子吸收截面上的$S_{22}$共振的比较,我们发现了一个通用的非共振吸收,原来是一个等效的石墨烯片的数量级的一半。该值以及非共振窗口中的吸收线形状与基于密度矩阵形式主义的微观计算非常一致。半导体纳米管的这种非共振吸收在0.5~eV宽的窗口内基本上与频率无关,并且在$S_{11}$和$S_{22}$共振之间或在$S_{22}$和$S_{33}$共振之间达到近似相同的值。此外,非共振吸收截面证明是相同的所有手性物种,我们在这项研究中测量。从实践的角度来看,本研究通过针对特定的激发波长,使给定直径范围内样品的所有手性物质几乎均匀激发,为基于光致发光研究的样品含量分析奠定了坚实的基础。

英文摘要:

Photoluminescence excitation measurements in semi-conducting carbon nanotubes show a systematic non-resonant contribution between the well known excitonic resonances. Using a global analysis method, we were able to delineate the contribution of each chiral species including its tiny non-resonant component. By comparison with the recently reported excitonic absorption cross-section on the $S_{22}$ resonance, we found a universal non-resonant absorbance which turns out to be of the order of one half of that of an equivalent graphene sheet. This value as well as the absorption line-shape in the non-resonant window is in excellent agreement with microscopic calculations based on the density matrix formalism. This non-resonant absorption of semi-conducting nanotubes is essentially frequency independent over 0.5~eV wide windows and reaches approximately the same value betweeen the $S_{11}$ and $S_{22}$ resonances or between the $S_{22}$ and $S_{33}$ resonances. In addition, the non-resonant absorption cross- section turns out to be the same for all the chiral species we measured in this study. From a practical point of view, this study puts firm basis on the sample content analysis based on photoluminescence studies by targeting specific excitation wavelengths that lead to almost uniform excitation of all the chiral species of a sample within a given diameter range.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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