Manipulation and Raman Spectroscopy with Optically Trapped Metal Nanoparticles Obtained by Pulsed Laser Ablation in Liquids
Manipulation and Raman Spectroscopy with Optically Trapped Metal Nanoparticles Obtained by Pulsed Laser Ablation in Liquids
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DOI：
10.1021/jp109405j
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发表时间：
2011-03-31
影响因子：
3.7
通讯作者：
Marago, O. M.
中科院分区：
文献类型：
--
作者：
Messina, E.;Cavallaro, E.;Marago, O. M.
我们从实验和理论上研究了金属纳米粒子和聚集体的光学捕获。特别是，我们展示了如何利用光力捕获单个金纳米聚集体，这些聚集体的大小和结构由激光烧蚀合成得到。由于它们的表面电荷，在捕获实验中没有观察到孤立的纳米颗粒的团聚，通过分析陷阱中的布朗运动，可以可靠地测量孤立和聚集的纳米颗粒的光学力。我们展示了这些纳米结构的场增强特性如何使吸附在拉曼镊子装置中光学捕获的聚集体上的分子的表面增强拉曼光谱成为可能。最后，我们讨论了基于全电磁散射理论的聚集态金纳米结构的消光和光学力的计算，其中长波长等离子体激元共振的出现对捕获力的增强起着至关重要的作用。
We investigate experimentally and theoretically optical trapping of metal nanoparticles and aggregates. In particular, we show how light forces can be used to trap individual gold nanoaggregates of controlled size and structure obtained by laser ablation synthesis in solution. Due to their surface charge, no agglomeration of isolated nanoparticles was observed during trapping experiments and reliable optical force measurements of isolated and aggregated nanoparticles was possible through an analysis of the Brownian motion in the trap. We show how the field-enhancement properties of these nanostructures enables surface-enhanced Raman spectroscopy of molecules adsorbed on aggregates optically trapped in a Raman tweezers setup. We finally discuss calculations of extinction and optical forces based on a full electromagnetic scattering theory for aggregated gold nanostructures where the occurrence of plasmon resonances at longer wavelength play a crucial role in the enhancement of the trapping forces.