Kim Deok-Soo, Heo Jinhwa, Ahn Sung-Hyun, Han Sang Woo, Yun Wan Soo, Kim Zee Hwan
Department of Chemistry and BK21 Division of Chemistry, Korea University, Seoul 136-701, Korea.
Nano Lett. 2009 Oct;9(10):3619-25. doi: 10.1021/nl901839f.
We carried out the near-field optical imaging of isolated and dimerized gold nanocubes to directly investigate the strong coupling between two adjacent nanoparticles. The high-resolution (approximately 10 nm) local field maps (intensities and phases) of self-assembled nanocube dimers reveal antisymmetric plasmon modes that are starkly different from a simple superposition of two monomeric dipole plasmons, which is fully reproduced by the electrodynamics simulations. The result decisively proves that, for the closely spaced pair of nanoparticles (interparticle distance/particle size approximately 0.04), the strong Coulombic attraction between the charges at the interparticle gap dominates over the intraparticle charge oscillations, resulting in a hybridized dimer plasmon mode that is qualitatively different from those expected from a simple dipole-dipole coupling model.
我们对孤立的和二聚化的金纳米立方体进行了近场光学成像，以直接研究两个相邻纳米颗粒之间的强耦合。自组装纳米立方体二聚体的高分辨率（约10纳米）局部场图（强度和相位）揭示了反对称等离子体模式，该模式与两个单体偶极等离子体的简单叠加截然不同，这一结果在电动力学模拟中得到了完全重现。该结果明确证明，对于间距紧密的一对纳米颗粒（颗粒间距离/颗粒尺寸约为0.04），颗粒间间隙处电荷之间的强库仑吸引力超过了颗粒内电荷振荡，从而产生了一种与简单偶极-偶极耦合模型预期的模式在性质上不同的杂化二聚体等离子体模式。
