Du Guangqing, Lu Yu, Lankanath Dayantha, Hou Xun, Chen Feng
State Key Laboratory for Manufacturing System Engineering and Shaanxi Key Laboratory of Photonics Technology for Information, School of Electronic Science and Engineering, Xi'an Jiaotong University, Xi'an 710049, China.
Materials (Basel). 2022 Jul 1;15(13):4627. doi: 10.3390/ma15134627.
We theoretically investigated the plasmon trapping stability of a molecular-scale Au sphere via designing Au nanotip antenna hybridized with a graphene sheet embedded Silica substrate. A hybrid plasmonic trapping model is self-consistently built, which considers the surface plasmon excitation in the graphene-hybridized tip-substrate system for supporting the scattering and gradient optical forces on the optical diffraction-limit broken nanoscale. It is revealed that the plasmon trapping properties, including plasmon optical force and potential well, can be unprecedentedly adjusted by applying a graphene sheet at proper Fermi energy with respect to the designed tip-substrate geometry. This shows that the plasmon potential well of 218 kT at room temperature can be determinately achieved for trapping of a 10 nm Au sphere by optimizing the surface medium film layer of the designed graphene-hybridized Silica substrate. This is explained as the crucial role of graphene hybridization participating in plasmon enhancement for generating the highly localized electric field, in return augmenting the trapping force acting on the trapped sphere with a deepened potential well. This study can be helpful for designing the plasmon trapping of very small particles with new routes for molecular-scale applications for molecular-imaging, nano-sensing, and high-sensitive single-molecule spectroscopy, etc.
我们通过设计与嵌入二氧化硅衬底的石墨烯片杂交的金纳米尖天线，从理论上研究了分子尺度金球体的等离子体捕获稳定性。自洽地建立了一个混合等离子体捕获模型，该模型考虑了石墨烯杂交的尖端-衬底系统中的表面等离子体激发，以支持在光学衍射极限突破的纳米尺度上的散射和梯度光学力。结果表明，通过在相对于设计的尖端-衬底几何结构的适当费米能量下应用石墨烯片，可以前所未有的方式调节等离子体捕获特性，包括等离子体光学力和势阱。这表明，通过优化设计的石墨烯杂交二氧化硅衬底的表面介质膜层，在室温下可以确定地实现218 kT的等离子体势阱，用于捕获10 nm的金球体。这可以解释为石墨烯杂交在等离子体增强中发挥关键作用，以产生高度局部化的电场，进而增强作用在被捕获球体上的捕获力，并加深势阱。这项研究有助于设计用于分子成像、纳米传感和高灵敏度单分子光谱等分子尺度应用的新途径来捕获非常小的粒子的等离子体。
