Near-field imaging of optical field and plasmon wavefunctions in metal nanoparticles
Near-field imaging of optical field and plasmon wavefunctions in metal nanoparticles
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DOI：
10.1039/b607147c
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发表时间：
2006-10
影响因子：
--
通讯作者：
H. Okamoto;K. Imura
中科院分区：
文献类型：
--
作者：
H. Okamoto;K. Imura
扫描近场光学显微镜使光学测量和观察的空间分辨率远远超过光的衍射极限。这使我们能够在空间上解析纳米颗粒的位置，同时逐点研究光谱特性。在这篇专题文章中，我们专注于各向异性金纳米粒子和聚集体（纳米棒，三角形纳米片和聚集的纳米球）中表面等离子体的近场显微镜研究。我们利用线性透射/散射以及非线性双光子激发测量在近场，观察局部电场或电磁局域态密度。我们表明，在纳米粒子与入射辐射场共振的等离子体激元激发的波函数是可视化的近场方法。在聚集的纳米粒子，强电场增强定位在间隙网站，这是理论上预测以前，清楚地成像，其主要贡献表面增强拉曼散射也显示了近场图像。
Scanning near-field optical microscopes enable optical measurements and observations with a spatial resolution far beyond the diffraction limit of light. This allows us to spatially resolve the positions in nanoparticles and at the same time to investigate spectroscopic characteristics point by point. In this feature article, we focus on near-field microscopic studies on surface plasmons in anisotropic gold nanoparticles and aggregates (nanorods, triangular nanoplates, and aggregated nanospheres). We have utilized linear transmission/scattering as well as nonlinear two-photon excitation measurements in the near field, to observe the local electric field or electromagnetic local density of states. We show that the wavefunction of the plasmon excitation in the nanoparticle resonant with the incident radiation field is visualized by the near-field methods. In the aggregated nanoparticles, strong electric-field enhancement localized in the interstitial sites, which was theoretically predicted previously, is clearly imaged, and its major contribution to surface enhanced Raman scattering is also shown by the near-field images.