Size Effect on SERS of Gold Nanorods Demonstrated via Single Nanoparticle Spectroscopy
Size Effect on SERS of Gold Nanorods Demonstrated via Single Nanoparticle Spectroscopy
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DOI：
10.1021/acs.jpcc.6b02098
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发表时间：
2016-09-22
影响因子：
3.7
通讯作者：
Ren, Bin
中科院分区：
文献类型：
--
作者：
Lin, Kai-Qiang;Yi, Jun;Ren, Bin
表面增强拉曼光谱（SERS）作为一种无标记的高灵敏度分析方法引起了人们的极大兴趣。为了优化SERS活性，系统地研究纳米颗粒的尺寸效应对SERS增强的影响是非常重要的，这在实验中是一个挑战，因为纳米颗粒的局部表面等离子体共振（LSPR）也随着粒径的变化而变化。这一挑战可以通过利用金纳米棒的独特性质来克服，通过适当选择纳米棒的尺寸和纵横比，可以控制其LSPR波长相同。我们在自制的单纳米颗粒光谱系统上获得了相关的SEM图像、散射光谱和SERS光谱，并以吸附的异硫氰酸孔雀石绿（malachite green isothiocyanate， MGITC）分子为探针分子，系统地研究了尺寸对单个金纳米棒SERS的影响。暗场散射强度随着纳米粒子尺寸的增大而增大，而SERS强度则随着尺寸的减小而增大，这是由于避雷针效应的增强和辐射阻尼的减弱。我们进一步探索了耦合纳米棒二聚体体系的尺寸依赖效应。当激发接近LSPR波长时，SERS活性随粒径的减小而增加。了解尺寸对局部场增强的影响有助于设计和制造具有高SERS活性的SERS衬底和SERS针尖。
Surface-enhanced Raman spectroscopy (SERS) has attracted tremendous interest as a label-free highly sensitive analytical method. For optimization of SERS activity, it is highly important to systematically investigate the size effect of nanoparticles on the SERS enhancement, which appears to be challenging in experiment, as the localized surface plasmon resonance (LSPR) of nanoparticles also changes with the change of the particle size. This challenge can be overcome by utilizing the unique property of gold nanorods, whose LSPR wavelength can be controlled to be the same by properly choosing the size and aspect ratio of the nanorods. We obtained the correlated SEM images, scattering spectra, and SERS spectra on a home-built single nanoparticle spectroscopy system and systematically investigate the size effect on SERS of individual gold nanorods using the adsorbed malachite green isothiocyanate (MGITC) molecule as the probe molecule. The dark field scattering intensity was found to increase with the increase of the size of nanoparticles, whereas the SERS intensity increases with the decrease of the size as a result of the stronger lightning rod effect and weaker radiation damping. We further explored the size-dependent effect for the coupled nanorod dimer system. The SERS activity was also found to increase with a decrease of the particle size when the excitation is close to the LSPR wavelength. Understanding of the size effect on the local field enhancement may help to design and fabricate SERS substrate and TERS tips with high SERS activity.