Shape and size effects in the optical properties of metallic nanorods
Shape and size effects in the optical properties of metallic nanorods
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DOI：
10.1039/b518389h
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发表时间：
2006-01-01
影响因子：
3.3
通讯作者：
Poelsema, Bene
中科院分区：
文献类型：
--
作者：
Kooij, E. Stefan;Poelsema, Bene
采用离散偶极近似（DDA）方法研究了尺寸和几何形状对随机取向金属纳米棒光学性质的影响。我们的计算提供了一个基准的纳米棒悬浮液经常使用的光学光谱技术的准确表征。我们的DDA结果证实了纵向等离子体共振主要受纳米棒纵横比的影响，并且还验证了椭圆形颗粒的准静态（偶极）近似仅对非常小的尺寸有效。对于具有相同纵横比的长椭圆形和圆柱形纳米棒，后者在显著更长的波长处表现出纵向共振。较大的纳米棒尺寸的相位延迟和多极贡献的重要性进行了讨论。此外，我们调查的电子表面散射，这是由有限的尺寸的纳米棒相比，电子平均自由程的光学光谱的影响。
The influence of size and geometrical shape on the optical properties of randomly oriented metallic nanorods is investigated using the discrete dipole approximation (DDA). Our calculations provide a benchmark for an accurate characterisation of nanorod suspensions by frequently used optical spectroscopic techniques. Our DDA results confirm the longitudinal plasmon resonance to be primarily affected by the nanorod aspect ratio, and also verify that the quasi-static (dipole) approximation for ellipsoidal particles is only valid for very small sizes. For prolate ellipsoidal and cylindrical nanorods with an identical aspect ratio, the latter exhibit a longitudinal resonance at significantly longer wavelengths. The importance of phase retardation and multipole contributions for larger nanorod dimensions is discussed. Also, we investigate the influence on the optical spectra of electron surface scattering, which arises from the limited size of the nanorods in comparison to the electron mean free path.