Itoh Tamitake, Biju Vasudevanpillai, Ishikawa Mitsuru, Kikkawa Yasuo, Hashimoto Kazuhiro, Ikehata Akifumi, Ozaki Yukihiro
Nano-Bioanalysis Team, Health Technology Research Center, National Institute for Advanced Industrial Science and Technology, Takamatsu, Kagawa 761-0395, Japan.
J Chem Phys. 2006 Apr 7;124(13):134708. doi: 10.1063/1.2177662.
We investigated the optical properties of isolated single aggregates of Ag nanoparticles (Ag nanoaggregates) on which rhodamine 6G molecules were adsorbed to reveal experimentally a correlation among plasmon resonance Rayleigh scattering, surface-enhanced resonance Raman scattering (SERRS), and its background light emission. From the lack of excitation-laser energy dependence of background emission maxima we concluded that the background emission is luminescence, not Raman scattering. The polarization dependence of both SERRS and background emission was the same as that of the lowest-energy plasmon resonance maxima, which is associated with a longitudinal plasmon. From the common polarization dependence, we identified that the lowest-energy plasmon is coupled with both SERRS and background emission. In addition, we revealed that the lowest-energy plasmon with a higher quality factor (Q factor) yields larger SERRS and background emission intensity. Also, we identified that the Q factor dependence of the SERRS intensity was similar to that of the background emission intensity. This similarity directly supported us to demonstrate an enhancement of both SERRS and background emission by coupling with a common plasmon radiative mode.
我们研究了吸附有罗丹明6G分子的孤立银纳米颗粒单聚集体（银纳米聚集体）的光学性质，以通过实验揭示等离子体共振瑞利散射、表面增强共振拉曼散射（SERRS）及其背景光发射之间的相关性。由于背景发射最大值缺乏对激发激光能量的依赖性，我们得出结论，背景发射是发光，而非拉曼散射。SERRS和背景发射的偏振依赖性与最低能量等离子体共振最大值的偏振依赖性相同，这与纵向等离子体相关。基于共同的偏振依赖性，我们确定最低能量等离子体与SERRS和背景发射均耦合。此外，我们发现具有较高品质因数（Q因子）的最低能量等离子体产生更大的SERRS和背景发射强度。而且，我们确定SERRS强度的Q因子依赖性与背景发射强度的Q因子依赖性相似。这种相似性直接支持我们证明通过与共同的等离子体辐射模式耦合来增强SERRS和背景发射。
