Cheng Zi-Qiang, Nan Fan, Yang Da-Jie, Zhong Yu-Ting, Ma Liang, Hao Zhong-Hua, Zhou Li, Wang Qu-Quan
Key Laboratory of Artificial Micro- and Nano-structures of the Ministry of Education, and School of Physics and Technology, Wuhan University, Wuhan, 430072, P.R. China.
Nanoscale. 2015 Jan 28;7(4):1463-70. doi: 10.1039/c4nr05544f.
Seeking plasmonic nanostructures with large field confinement and enhancement is significant for photonic and electronic nanodevices with high sensitivity, reproducibility, and tunability. Here, we report the synthesis of plasmonic arrays composed of two-segment dimer nanorods and coaxial cable nanorods with ∼1 nm gap insulated by a self-assembled Raman molecule monolayer. The gap-induced plasmon coupling generates an intense field in the gap region of the dimer junction and the cable interlayer. As a result, the longitudinal plasmon resonance of nanorod arrays with high tunability is obviously enhanced. Most interestingly, the field enhancement of dimer nanorod arrays can be tuned by the length ratio L1/L2 of the two segments, and the maximal enhancement appears at L1/L2 = 1. In that case, the two-photon luminescence (TPL) of dimer nanorod arrays and the Raman intensity in the dimer junction is enhanced by 27 and 30 times, respectively, under resonant excitation. In the same way, the Raman intensity in the gap region is enhanced 16 times for the coaxial cable nanorod arrays. The plasmonic nanorod arrays synthesized by the facile method, having tunable plasmon properties and large field enhancement, indicate an attractive pathway to the photonic nanodevices.
寻找具有大场限制和增强作用的等离子体纳米结构对于具有高灵敏度、可重复性和可调谐性的光子和电子纳米器件具有重要意义。在此，我们报道了由两段式二聚体纳米棒和同轴电缆纳米棒组成的等离子体阵列的合成，其间隙约为1 nm，由自组装拉曼分子单层绝缘。间隙诱导的等离子体耦合在二聚体结和电缆夹层的间隙区域产生强场。结果，具有高可调谐性的纳米棒阵列的纵向等离子体共振明显增强。最有趣的是，二聚体纳米棒阵列的场增强可以通过两段的长度比L1/L2来调节，最大增强出现在L1/L2 = 1时。在这种情况下，在共振激发下，二聚体纳米棒阵列的双光子发光（TPL）和二聚体结中的拉曼强度分别增强了27倍和30倍。同样，同轴电缆纳米棒阵列间隙区域的拉曼强度增强了16倍。通过这种简便方法合成的等离子体纳米棒阵列具有可调谐的等离子体特性和大场增强，为光子纳米器件指明了一条有吸引力的途径。
