角分辨光谱测量系统的建立及其在可控定向SERS基底光学表征中的应用

High sensitivity and high uniformity are guarantees for wide applying of surface enhanced Raman spectroscopy (SERS). SERS on two-dimensional periodic metallic nanostructures, which have so called localized surface plasmon resonance (LSPR) and surface propagation plasmon(SPP), can be tuned by controlling morphology of nanostructures and have higher exciting and collecting efficiency. Normally, such a structure presents highly angular dependency, and if the exciting and collecting directions are designed appropriately, a higher sensitivity can be gotten on a highly uniform surface, and presents a reproducibility of SERS signal. In this project, we want to establish a complete spectroscopy approach, which is based on SERS and includes absorption spectrum and transmission spectrum,to reseach the characterization of directional SERS substrates.A novel angle resolved confocal micro-Raman spectrum measurement system will be established by dividing the entrance pupil of a high numerical aperture microscopic objective lens to partitions of exciting and collecting,one can change the exciting and the collecting angle by moving these partitions independently in a large angle range without any mechanical interference,and by adjusting these partition sizes, one can change the exciting and the collecting aperture. A macro angle-resolved spectral measuring system based on rotational stages will be also established , and it will be developed to a universal spectroscopic characterization approach for directional SERS substrates. Using controllable large area highly ordered two-dimensional periodic metallic nanostructure as systematic experimental objects, characterization experiments, as well as theoretical computings and simulations will be carried out, and relationship between the morphology of periodic metallic nanostructure , directional SPP/SPR and directional SERS will be reseached.

高检测灵敏度和高信号重现性是表面增强拉曼光谱（SERS）走向广泛应用的保障。二维周期性金属纳米结构充分利用局域化的和传播型的表面等离激元共振（LSPR和SPP），可通过调控结构参数获得最佳的SERS激发效率。这样的结构通常有很强的定向性，若合理设计激发和收集角度，有可能获得最高的灵敏度并提供高度均匀的表面，保障信号的重现性。本课题拟建立具有角分辨能力的光谱检测系统、包含反射、吸收和拉曼光谱等，对有序SERS基底进行全方位的光谱表征。拟通过光路设计将高数值孔径显微物镜的孔径划分为激发和收集分区，实现大角度范围连续的角分辨显微光学测量。拟建立基于转臂的角分辨光谱宏光路测量系统，并发展成定向SERS基底的光谱学通用表征手段。以紫外干涉刻蚀法制备的形貌可控、高度有序的二维周期性纳米结构为对象，结合理论模拟，研究结构表面微区形貌、表面等离激元的定向激发/共振/传播以及SERS定向发射之间的定量规律。

表面等离激元结构与入射光波发生相互作用,即发生表面等离激元共振 (surface plasmon resonance, SPR)作用时,伴随着局域电磁场的增强和对光在低于衍射极限尺度上的束缚。因此被广泛的用于表面增强光谱、生物化学传感、 太阳能光伏器件、光催化等领域。其中表面增强的拉曼光谱(surface-enhanced Raman spectroscopy, SERS)和生物化学传感器(bio-chemical sensor)是SPR现象的两个最主要的应用途径。高度有序的二维周期性金属纳米结构是典型的表面等离激元结构，其表面等离激元共振的激发、传播和发射都具有很强的定向特性。.因此本项目针对SPP/SPR的角分辨特性，发展了可控SPR纳米结构的制备方法，建立了纳米结构基底的角分辨光谱特性表征手段，结合理论模拟，研究了结构表面微区形貌与其SPs和SERS及各种角分辨光谱特性之间的定量规律具体的研究成果体现在：1、自主设计并搭建了一套基于数值孔径分区方法的角分辨光谱测量系统：相比传统的后焦面角分辨光谱测量系统，该系统具有更高的微区空间、角度分辨率。另外，该系统搭载了高速、高增益的EMCCD以及具有高精度窄带滤波能力的LCTF来采集光谱，相比传统的后焦面角分辨光谱系统具有更高的时间、光谱分辨率； 2、自主设计并搭建了一套改进型的转臂式角分辨光谱测量系统：相比于传统转臂角分辨技术，该系统采用电动转盘与转臂非刚性连接的机械设计，保证转臂同心转动，并且增加了样品平台水平方向的旋转自由度，提高了实验灵活性； 3、设计并实现了紫外激光全息光刻系统，为制备形貌可控的二维周期性纳米金属结构提供了保障；4、研究了二维周期性纳米结构的微区形貌与SPs/SPP激发与发射之间的相关性，为进一步设计和制备形貌可控的、具有更高灵敏度的SERS基底奠定了基础。.相关的研究成果以学术论文的方式发表，其中SCI/EI期刊收录6篇（1区1篇，2区1篇，3区2篇，4区1篇），投稿1篇（1区）。国内外会议论文3篇。获授权国家发明专利3项，申请1项。课题组培养了博士研究生2人，硕士研究生4人。本项目课题进展基本按预期计划，成果超额完成了任务。