One-dimensional plasmonic hotspots located between silver nanowire dimers evaluated by surface-enhanced resonance Raman scattering
One-dimensional plasmonic hotspots located between silver nanowire dimers evaluated by surface-enhanced resonance Raman scattering
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DOI：
10.1103/physrevb.95.115441
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发表时间：
2017-03-31
影响因子：
3.7
通讯作者：
Balachandran, Jeyadevan
中科院分区：
文献类型：
--
作者：
Itoh, Tamitake;Yamamoto, Yuko S.;Balachandran, Jeyadevan
表面增强共振拉曼散射（SERRS）的热点位于等离子体纳米颗粒二聚体的间隙或裂缝处的1 nm内。我们展示了SERRS热点与体积在一维扩展数万倍相比，标准的零维热点使用等离子体纳米线二聚体的裂缝。根据偏振测量，在沿着二聚体宽度的方向上的等离子体共振产生SERRS热点。SERRS图像显示热点边缘之间的振荡模式。SERRS强度在边缘处变得最强，表明表面等离子体的Fabry-Perot型共振参与了拉曼增强。这些光学性质的SERRS热点的电磁（EM）机制的基础上通过数值计算定量再现。染料分子激子和等离子体激元之间的EM耦合能量使用在热点处的SERRS活性损失中反映的等离子体激元共振中的光谱变化来评估。耦合能与计算的电磁增强因子是一致的。
Hotspots of surface-enhanced resonance Raman scattering (SERRS) are localized within 1 nm at gaps or crevices of plasmonic nanoparticle dimers. We demonstrate SERRS hotspots with volumes that are extended in one dimension tens of thousand times compared to standard zero-dimensional hotspots using crevices of plasmonic nanowire dimers. According to the polarization measurements, a plasmon resonance in the direction along the dimer width generates SERRS hotspots. SERRS images show oscillating patterns between edges of the hotspot. The SERRS intensity becomes the strongest at the edges, indicating that Fabry-Perot-type resonance of surface plasmons is involved in the Raman enhancement. These optical properties of the SERRS hotspots are quantitatively reproduced by numerical calculations based on the electromagnetic (EM) mechanism. EM coupling energy between dye molecule excitons and plasmons is evaluated using spectral changes in plasmon resonance reflected in a loss of SERRS activity at the hotspots. The coupling energies are consistent with the calculated EM enhancement factors.