Enhanced collective optical response of vast numbers of silver nanoparticles assembled on a microbead
Enhanced collective optical response of vast numbers of silver nanoparticles assembled on a microbead
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DOI：
10.1007/s11164-014-1610-0
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发表时间：
2014-03
影响因子：
3.3
通讯作者：
S. Tokonami;K. Nishida;Yushi Nishimura;S. Hidaka;Yojiro Yamamoto;H. Nakao;T. Iida
中科院分区：
文献类型：
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作者：
S. Tokonami;K. Nishida;Yushi Nishimura;S. Hidaka;Yojiro Yamamoto;H. Nakao;T. Iida
我们研究了大量的银纳米颗粒（AgNPs）密集组装在有机微球上的光学响应，即，在局部表面等离子体激元的集体现象下，AgNP固定的珠。为此，在水溶液中通过暗场光学显微镜和激光拉曼显微镜分析了这种AgNP固定珠的各种光学性质。特别是，在与单一银纳米粒子的光谱相比，显着的光谱展宽和红移观察到由于等离子体超辐射与减少粒子间的距离到亚纳米级时，使用小粘合剂分子在银纳米粒子固定珠。此外，我们观察到表面增强的拉曼散射和澄清的灵敏度的信号强度之间的粘合剂分子的大小的AgNP，这可以解释基于光学响应理论使用离散积分与球形细胞。这些结果和讨论为宽带等离子体光吸收剂以及基于由自下而上的自组装过程产生的大量纳米间隙的小分子和纳米级生物材料的高灵敏度检测提供了指导原则。
We investigated the optical response of a huge number of silver nanoparticles (AgNPs) densely assembled on an organic microsphere, i.e., AgNP-fixed bead, under the collective phenomena of localized surface plasmons. For this purpose, various optical properties of such a AgNP-fixed bead were analyzed in aqueous solution by dark-field optical microscopy and laser Raman microscopy. In particular, in comparison with the optical spectrum of single AgNPs, significant spectral broadening and redshift were observed due to plasmonic superradiance with decreasing interparticle distance to the subnanoscale when using small binder molecules in the AgNP-fixed bead. Furthermore, we observed surface-enhanced Raman scattering and clarified the sensitivity of the signal intensity to the size of the binder molecules between the AgNPs, which can be explained based on optical response theory using a discrete integral with spherical cells. These results and discussion provide a guiding principle for broadband plasmonic light absorbers and for highly sensitive detection of small molecules and nanoscale biomaterials based on vast numbers of nanogaps produced by a bottom-up self-assembly process.