基于分子探针与多层结构纵向自耦合效应的相干拉曼成像研究

Coherent Raman scattering imaging defeat spontaneous Raman imaging on weak signal and long acquisition time through the pump and probe method, which prove significant applications on drug delivery, molecular diagnosis and gene tagging. However, the scattering and absorbing below the surface of tissue always lead to the limitation by blurring image quality, include resolution, contrast and acquisition rate. To solve this point, combined with nanostructures and nanoparticles, the enhancement in the radiative rate and radiative efficiency can be obtained through the principle called localized surface plasmon. In this proposal, high-efficiency Raman imaging can be resolved from the enhancement of noble nanoparticles and probe-film structure. The background technique of surface wave coupled emission and surface enhanced Raman scattering will be demonstrated in coherent Raman imaging when detecting and collecting signals, after updating this new longitudinal coupled structure from traditional glass substrate. Meanwhile, the mechanism of enhancement and gap-related parameters will be well studied. The results will be very helpful for developing a new kind of characterization technique in nanophotonics and biophotonics.

相干拉曼成像技术利用泵浦-探测手段解决了自发拉曼光谱信号弱、不易探测等问题，在药物传递，分子诊断，基因定位等多方面都有着重要的应用价值。但是由于生物样品的复杂多样性而带来的众多散射、吸收问题依旧会导致收集效率的降低，从而使成像的速率、分辨率等关键因素受到影响，局限了此技术的更广泛应用。而常见的纳米粒子及各类二维复合结构的表面局域效应可以有效地增强其近场的电场强度，大幅度提高探测信号的发射速率和辐射效率。本项目旨在通过研究样品自身与颗粒多层膜结构的纵向耦合调控来提升相干拉曼成像水平，提出新型高效的光谱成像方法。申请人将预研所得的荧光定向辐射技术、灵敏度可达单分子检测水平的表面增强技术运用于拉曼光谱的检测与成像中，分析研究微纳结构间的光场转化与增强机制，揭示具体的间距结构调控方法，研究高效场增强与参数的依赖关系；同时优化成像技术中的传统衬底，完成弱信号的检测和快速收集，发展新型表征技术。

在项目的资助下，我们取得了以下几方面的研究进展：1）揭示纵向耦合体系中的定向辐射机制，提出了非简并耦合辐射的概念，发展了光谱解析的新原理、新方法，研制了具有超薄结构的光谱表征设备；2）阐明了成像系统对探针分子表征的机理和条件，提出了分子取向的判定方式；3）提出了分子间距判定公式，发展了新的计算方案，为近场多分子表征奠定了基础；4）发展了多波长分子纵向定位技术，实现了远离界面处的分子高分辨定位；5）研制了具有多层结构的金属-光子晶体结构，发展了不受外界环境干扰的定向辐射，以及对应的自参考传感应用；6）首次在实验中展示纳米孔洞中荧光团与塔姆等离激元的耦合，在生物分析和生物科学中具有潜在的应用前景。.