Dark-field microscopy studies of single metal nanoparticles: understanding the factors that influence the linewidth of the localized surface plasmon resonance
Dark-field microscopy studies of single metal nanoparticles: understanding the factors that influence the linewidth of the localized surface plasmon resonance
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DOI：
10.1039/b714759g
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发表时间：
2008-01-01
影响因子：
--
通讯作者：
Hartland, Gregory V.
中科院分区：
文献类型：
--
作者：
Hu, Min;Novo, Carolina;Hartland, Gregory V.
本文综述了近年来对单金属纳米颗粒的瑞利散射测量。我们将详细讨论两种不同的系统：长度在30到80纳米之间，宽度在8到30纳米之间的金纳米棒；以及中空的金银纳米立方体（根据其确切的形态称为纳米盒或纳米笼），边缘长度在100到160纳米之间，壁厚约为10纳米。这项工作的目标是了解局部表面等离子体共振的线宽如何取决于纳米颗粒的大小、形状和环境。具体来说，通过检查不同尺寸的粒子，确定了体失相、电子表面散射和辐射阻尼（通过耦合到辐射场的能量损失）的相对贡献。这种分离是可能的，因为辐射阻尼效应的大小与粒子体积成正比，而电子表面散射的贡献与尺寸成反比。对于纳米棒，辐射阻尼是粗棒（宽度大于20 nm）的主导效应，而电子表面散射是细棒（宽度小于10 nm）的主导效应。宽度在这些限制之间的杆具有接近由体积贡献决定的值的窄共振。对于纳米盒和纳米笼，辐射阻尼和电子表面散射在所有尺寸下都是显著的。这是因为这些材料的壁很薄，但边缘长度很大，因此体积相对较大。研究了环境对纳米盒局部表面等离子体共振的影响。增加周围环境的介电常数会引起红移和等离子体带线宽的增加。线宽的增加是由于辐射阻尼的增强。
This article provides a review of our recent Rayleigh scattering measurements on single metal nanoparticles. Two different systems will be discussed in detail: gold nanorods with lengths between 30 and 80 nm, and widths between 8 and 30 nm; and hollow gold-silver nanocubes (termed nanoboxes or nanocages depending on their exact morphology) with edge lengths between 100 and 160 nm, and wall thicknesses of the order of 10 nm. The goal of this work is to understand how the linewidth of the localized surface plasmon resonance depends on the size, shape, and environment of the nanoparticles. Specifically, the relative contributions from bulk dephasing, electron-surface scattering, and radiation damping (energy loss via coupling to the radiation field) have been determined by examining particles with different dimensions. This separation is possible because the magnitude of the radiation damping effect is proportional to the particle volume, whereas, the electron-surface scattering contribution is inversely proportional to the dimensions. For the nanorods, radiation damping is the dominant effect for thick rods (widths greater than 20 nm), while electron-surface scattering is dominant for thin rods (widths less than 10 nm). Rods with widths in between these limits have narrow resonances approaching the value determined by the bulk contribution. For nanoboxes and nanocages, both radiation damping and electron-surface scattering are significant at all sizes. This is because these materials have thin walls, but large edge lengths and, therefore, relatively large volumes. The effect of the environment on the localized surface plasmon resonance has also been studied for nanoboxes. Increasing the dielectric constant of the surroundings causes a red-shift and an increase in the linewidth of the plasmon band. The increase in linewidth is attributed to enhanced radiation damping.