Plasmonic Nanoclusters: Near Field Properties of the Fano Resonance Interrogated with SERS
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- 作者：Jian Ye ; Fangfang Wen ; Heidar Sobhani ; J. Britt Lassiter ; Pol Van Dorpe ; Peter Nordlander ; Naomi J. Halas
- 刊名：Nano Letters
- 出版年：2012
- 出版时间：March 14, 2012
- 年：2012
- 卷：12
- 期：3
- 页码：1660-1667
- 全文大小：516K
- 年卷期：v.12,no.3(March 14, 2012)
- ISSN：1530-6992
文摘
While the far field properties of Fano resonances are well-known, clusters of plasmonic nanoparticles also possess Fano resonances with unique and spatially complex near field properties. Here we examine the near field properties of individual Fano resonant plasmonic clusters using surface-enhanced Raman scattering (SERS) both from molecules distributed randomly on the structure and from dielectric nanoparticles deposited at specific locations within the cluster. Cluster size, geometry, and interparticle spacing all modify the near field properties of the Fano resonance. For molecules, the spatially dependent SERS response obtained from near field calculations correlates well with the relative SERS intensities observed for individual clusters and for specific Stokes modes of a para-mercaptoaniline adsorbate. In all cases, the largest SERS enhancement is found when both the excitation and the Stokes shifted wavelengths overlap the Fano resonances. In contrast, for SERS from carbon nanoparticles we find that the dielectric screening introduced by the nanoparticle can drastically redistribute the field enhancement associated with the Fano resonance and lead to a significantly modified SERS response compared to what would be anticipated from the bare nanocluster.