基于高折射介电光学共振单元和金属等离激元晶体的复合型SERS基底的构建及性能研究

Surface-enhanced Raman scattering (SERS) is very promising in the analysis and detection of medical diagnosis, biosensing, trace materials, food safety and so on. However, there still lies one challenge to fabricate SERS-active substrates with high sensitivity and reproducibility of Raman signals. In this project, we propose to fabricate complex super-strong SERS-active substrates by combining high refractive index dielectric optical resonance units with metal plasmonic crystals and then study their performances and applications. The main contents include: 1) Design and controllable fabrication of complex super-strong SERS-active substrates with large area, low cost, stable repeatable and quasi-three-dimensional highly-dense distributed electromagnetic hot spots; 2) Study on the excitation modes of surface plasmon resonances and optics resonances, their resonant coupling condition and synergistic effect on the novel optical phenomena, and then mastering the internal mechanisms of resonant coupling; 3) Study on the hybridization and coupling of multiple surface plasmon resonances and the near-field field enhancement effects, far-field light scattering characteristics, novel optical phenomena and SERS effects caused by the multiple surface plasmon resonance coupling modified by the optical resonances, mastering their inner relationships and then revealing the relevant physical mechanisms. These studies would lad the foundation for the research and applications of the novel composite super-strong SERS-active substrates based on high refractive dielectric optical resonance units and metal plasmonic crystals.

表面增强拉曼散射(SERS) 在医学诊断、生物传感、痕量物质、食品安全等的分析检测方面应用前景广阔，但要获得高灵敏且可重复的SERS信号，基底的制备是一个难点。本项目拟结合高折射介电光学共振单元和金属等离激元晶体构建复合型超强SERS活性基底，进而研究其性能和应用。主要内容包括：1）大面积、低成本、稳定可重复且电磁热点呈准三维高密度分布的复合型超强SERS活性基底的设计和可控制备；2）研究表面等离激元共振和光学共振的激发模式、共振耦合条件以及两者协同作用下的新奇光学现象，掌握其共振耦合的内在机制；3）研究多重表面等离激元共振的杂化耦合以及在光学共振调控下多重表面等离激元共振耦合导致的近场局域场增强效应、远场光散射特性、新奇光学现象及SERS效应，掌握其内在联系并揭示相关的物理机理，为基于高折射介质光学共振单元与金属等离激元晶体的新型复合型超强SERS活性基底的研究和应用奠定基础。

本项目以基于高折射介电共振单元和金属等离激元晶体的SERS基底结构为研究对象，研究了这些结构的可控化制备方法及光学性质，探索并揭示了在Mie共振-表面等离激元共振协同作用下SERS效应增强的本质，实现了超低浓度的分子检测。主要研究结果包括：1）首次提出并论证了一种基于物理电磁场和化学电荷转移效应同时增强被测分子拉曼信号的Au/介质/Au纳米颗粒结构SERS平台，讨论了高、低折射率介电共振单元对SERS增强效应的影响；2）设计并制备了一种基于金团簇-介质膜-金团簇复合型结构的新型准三维等离激元热点SERS平台，发现具有介电共振单元调控的SERS基底的SERS增强效应远强于无介电共振单元的SERS基底的增强效果，深入剖析了介电共振单元对SERS效应的增强机制；3）可控化制备了一种由金壳-Si壳-SiO2胶体晶体-金膜拼合而成的新型SERS活性基底，对比分析了等离激元对SERS效应调控的物理机理；4）探索了两种在SiO2胶体晶体阵列顶端沉积金纳米颗粒的SERS活性基底结构的可控化制备方法并研究了其SERS增强特性及机理；5）研究了由双层金纳米多孔膜结构堆叠而成的大面积、均匀、稳定且增强效果显著的SERS平台的简便且经济的可控化制备方法及其直达单分子检测水平的SERS检测极限，并阐述了该结构中SERS增强效应的物理本质；为基于介电光学共振单元和金属等离激元晶体的大面积、低成本且高性能的SERS基底结构的制造提供了令人印象深刻的视角，在SERS技术和SERS传感领域应用前景广阔。