Infrared Optical Properties of Nanoantenna Dimers with Photochemically Narrowed Gaps in the 5 nm Regime
Infrared Optical Properties of Nanoantenna Dimers with Photochemically Narrowed Gaps in the 5 nm Regime
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DOI：
10.1021/nn302429g
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发表时间：
2012-08-01
期刊：
影响因子：
17.1
通讯作者：
Haertling, Thomas
中科院分区：
文献类型：
--
作者：
Neubrech, Frank;Weber, Daniel;Haertling, Thomas
在本文中，我们报道了在红外（IR）光谱范围内共振的单个金纳米天线二聚体的近场耦合操作。光化学金属沉积在光刻制造的纳米天线上，可以将天线臂之间的间隙减小到4nm以下，正如有限差分时域模拟所证实的那样。隙区等离子体耦合的增加导致表面等离子体共振向较低能量的转移以及杂化等离子体模式的出现。所有发生的电子振荡模式都可以用等离子体杂化模型来解释。除了单个天线基共振的成键组合外，在正入射的红外透射率中也观察到反键组合。其外观是由于结构缺陷和天线之间的小间隙。本文对单个红外天线的详细分析使我们能够深刻理解光化学操作过程中发生的光谱特征，从而为亚纳米尺度间隙的全光学过程监测铺平了道路，这可能作为等离子体量子力学效应实验研究的模型系统。
In this paper, we report on the manipulation of the near-field coupling in individual gold nanoantenna dimers resonant in the infrared (IR) spectral range. Photochemical metal deposition onto lithographically fabricated nanoantennas is used to decrease the gap between the antenna arms down to below 4 nm, as confirmed by finite-difference time-domain simulations. The increased plasmonic coupling in the gap region leads to a shift of the surface plasmon resonances to lower energies as well as to the appearance of hybridized plasmonic modes. All of the occurring electron oscillation modes can be explained by the plasmon hybridization model. Besides the bonding combination of the fundamental resonances of individual antennas, also the antibonding combination is observed in the IR transmittance at normal incidence. Its appearance is due to both structural defects and the small gaps between the antennas. The detailed analysis of individual IR antennas presented here allows a profound understanding of the spectral features occurring during the photochemical manipulation process and therefore paves the way to a full optical process monitoring of sub-nanometer scale gaps, which may serve as model systems for experimental studies of quantum mechanical effects in plasmonics.