金属纳米结构的表面等离激元光学力研究

Plasmonics has become a popular and important research area, and has vast potential applications in multidiscipline. One of the most pronounced characteristics of surface plasmons is the electromagnetic (EM) field enhancement at the surface of metal nanostructures. The magnitude of the EM field decays rapidly with distance away from the surface, forming a sharp gradient of the field and giving rise to an attractive optical force that is capable of traping small molecues and nano-objects. An important branch of plasmonics has thus been developed, the so-called plasmonic forces. So far, some excellent publications have appeared on plasmonic forces, however, a number of important scientific questions, for example, the physical mechanism and the extension of optical forces and relevant applications, are still open and need to be further studied. This proposal will mainly deal with the physical principles and applications of plasmonic forces, including plasmonic forces induced by periodic EM field in one-dimensional metal nanostructures, the dynamic interactions between metal nanoparticles in an optical trap and spectroscopic response of DNA chains under stress by metal nanoparticles using laser tweezers. It aims at developing a new method for the characterization of single nanoparticles and extending novel applications of plasmonics in biology, and will enrich the knowledge in the understanding of light-matter interaction at the nanoscale.

表面等离激元光子学是目前国际上的前沿研究领域，具有广阔的应用前景。金属纳米结构的局域电磁场增强是表面等离激元共振的显著效应之一，电磁场的强度随离表面的距离急剧衰减，形成极强的电场梯度，导致光学力的产生，可以实现纳米尺度的光学操纵，并发展成为表面等离激元领域一个新兴的重要分支，即表面等离激元光学力。虽然已经有一些优秀工作发表，但在机理以及体系拓展和应用方面还有很多有待研究的重要内容。本项目将研究金属纳米结构表面等离激元光学力相关的物理机制问题和应用拓展，包括：利用一维金属纳米线和金属纳米光栅研究周期性电磁场近场的光学力，利用激光光镊技术研究光势阱中多粒子的动态相互作用，以及利用光镊技术操纵金属纳米颗粒探测生物DNA分子在应力作用下的表面增强光谱响应。本项目的实施将发展一种新型的单粒子表征手段，拓展表面等离激元在生物领域的应用方向，并将有助于从光学力的角度理解纳米尺度光与物质的相互作用。

本项目研究金属纳米结构表面等离激元光学力相关的物理机制和应用。在项目实施期间，搭建了基于1064 nm激光的光镊系统，实现了对介质纳米颗粒、金属纳米颗粒、金属纳米线的光学力捕获；与合作者共同从理论上计算了高斯激光照射下金属纳米颗粒的等离激元光学力效应，提出了金属纳米颗粒的尺寸选择性捕获；实现了金属纳米线中传播型表面等离激元对介质纳米颗粒的捕获，并通过结构设计，实现了对纳米颗粒的移动方向的选择性调制；实现了石墨烯/金属纳米结构复合基底的增强拉曼散射及其定量检测应用。. 通过本项目的实施，共发表论文12篇，含2篇ACS Nano，2篇JACS，1篇Nano Research，1篇Chem. Mater.，1篇Small和1篇Small Methods，其中，受邀撰写表面等离激元光学力相关的综述2篇（1篇ACS Nano，1篇《中国科学: 物理学 力学 天文学》）；申请专利3项；参加国际国内会议21次，做邀请报告11次；培养博士研究生4名，硕士研究生2名；完成了项目的预期指标。