Hsueh Chun-Hway, Lin Chih-Hong, Li Jia-Han, Hatab Nahla A, Gu Baohua
Department of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan.
Opt Express. 2011 Sep 26;19(20):19660-7. doi: 10.1364/OE.19.019660.
The discovery of single-molecule sensitivity via surface-enhanced Raman scattering on resonantly excited noble metal nanoparticles has brought an increasing interest in its applications to the molecule detection and identification. Periodic gold bowtie nanostructures have recently been shown to give a large enhancement factor sufficient for single molecule detection. In this work, we simulate the plasmon resonance for periodic gold bowtie nanostructures. The difference between the dipole and the quadrupole resonances is described by examining the magnitude and phase of electric field, the bound surface charge, and the polarization. The gap size dependence of the field enhancement can be interpreted by considering cavity field enhancement. Also, additional enhancement is obtained through the long-range collective photonic effect when the bowtie array periodicity matches the resonance wavelength.
通过共振激发的贵金属纳米颗粒上的表面增强拉曼散射实现单分子灵敏度的发现，引发了人们对其在分子检测和识别应用方面日益增长的兴趣。周期性金蝴蝶结纳米结构最近已被证明具有足以进行单分子检测的大增强因子。在这项工作中，我们模拟了周期性金蝴蝶结纳米结构的等离子体共振。通过检查电场的大小和相位、束缚表面电荷以及极化来描述偶极子和四极子共振之间的差异。场增强的间隙尺寸依赖性可以通过考虑腔场增强来解释。此外，当蝴蝶结阵列的周期性与共振波长匹配时，通过长程集体光子效应可获得额外的增强。
