介电环境、纳间隙构型对贵金属纳米天线表面等离激元量子效应的调控研究

表面等离激元量子效应为纳米尺度光调控提供了新的物理机制，使表面等离激元研究进入到量子范畴。表面等离激元量子效应主要发生在具有亚纳米间隙的金属纳米耦合结构中。然而，亚纳米间隙一直难以制备和测量，限制了量子效应在复杂体系中的观测及其在纳米光调控中的应用。申请人曾利用蒸发毛细力方法成功组装了亚纳米间隙的颗粒天线，结合电镜—暗场校准技术观测到单个量子纳米天线的发射退偏现象。基于该纳间隙组装技术，本项目进一步将研究体系拓展到不同形貌、构型的纳米颗粒体系中，研究纳间隙大小、构型（相对面积、角度）对量子表面等离激元共振的调控作用，如不同共振模式发射峰位、强度和偏振态变化等，揭示其作用过程、明确量子隧穿、非局域效应的发生区间；同时在实验中引入不同介质环境，如水、电解质溶液等，关注量子效应对介质折射率、导电率的光学响应特性，探索超灵敏光学传感的新方法；为发展基于量子效应的纳米光调控手段提供必要的研究基础。

Surface plasmon polaritons can enhance light-matter interactions and manipulate light at nanometer scale. One of the hottest current topics in plasmonics is quantum effects occurring at sub-nanometer gaps, including nonlocal screening and quantum tunneling, which can drastically alter both the far- and near-field properties of plasmonic nanoantennas, such as the spectral redistribution of plasmon modes and collapse of the field enhancement. Due to the very challenging in fabricating sub-nanometer gap structures, there is still no comprehensive experimental study about the dependence of plasmonic quantum effects on dielectric environments and nanogap morphologies which can greatly influence the surface plasmon coupling. In this project, we propose to obtain the dimer nanoantennas with different gap sizes down to sub-nanometer scale and morphologies (facing area and angle) by capillary drying force assembly method. By combining the microfluidics with dark-field microscope, the dark-field scattering of single nanoantenna can be in-situ detected in different dielectric environments, and the emission position, intensity and polarization of surface plasmon modes can be analyzed. The project will be carried out in three aspects: 1) the dielectric environments (refractivity and conductivity) dependence of plasmonic quantum effects, 2) the morphologies (facing area and angle of nanogaps) dependence of plasmonic quantum effects, 3) the plasmonic quantum effects in nanoparticle-nanowire coupling system, and the influence of quantum effects on surface plasmons emission intensity and polarization. The fulfillment of this proposal can not only deep our understanding on the manipulation of plasmonic quantum effects by dielectric environments and nanogap morphologies, but also pave the way to designing the quantum-controlled nanophotonic devices, such as the ultrasensitive sensor, and the plasmonic circuits for optics manipulation, etc.