金属微纳结构中表面荧光增强的理论研究

For the last few years, fluorescent probes have gained wide attention for its important role in application analysis methods. At the same time, the existence of surface enhanced fluorescence (SEF) phenomenon fully expand the scope of Fluorescence spectroscopy application. The combination of the both have been a front topic in recent years. However, the non-negligible difference between theoretical prediction and experimental results hugely restricts the practical application of SEF. The main target of this program is to reveal interaction between fluorescent probes and surface metallic micro nano-structures, building a much perfect model of SEF in quantum framework. This include the coupled modes of surface plasmon polaritions in different surface metallic micro nano-structures ,and the features of local field; studying the relationship among excitation process, radiation process, enhancement process and local field enhancement, and modeling for SEF in quantum theory format ; correcting the model for taking account of higher order interaction, clarifying the mechanism of fluorescence quenching and proposing the theoretical criterion to distinguish fluorescence enhanced or quenching; proposing a theoretical scheme to realize the active control SEF. The above studies are beneficial for deeply understanding the principles of SEF, as well as for extending the application of fluorescent probes and SEF.

近些年来，荧光探针技术作为重要的应用分析手段为人们广泛关注；同时表面荧光增强现象的存在极大的拓展了荧光光谱学的应用范围，两者的结合是目前研究的前沿课题。然而现有表面荧光增强的理论预测与实验结果存在的较大的差距，极大的限制了表面荧光增强的实际应用。本项目拟从量子理论角度出发，研究荧光探针分子与表面金属结构的相互作用，建立更精确描述表面荧光增强现象的理论模型。首先，利用不同表面金属结构与荧光的相互作用，实现不同的表面等离激元耦合模式，获得不同的局域电场特性；其次，用量子化方法精确、完整地描述探针分子的荧光激发、辐射、增强过程与局域电场的量子相互作用，建立一个表面荧光增强的量子理论模型；随后研究高阶相互作用对模型的修正，并合理解释荧光猝灭的物理机制，提出荧光猝灭的量子判据；最后，设计理论方案实现表面荧光增强的主动控制。本项目对深入理解表面荧光增强的物理机制、推广荧光技术的应用范围具有重要意义。

荧本项目从量子理论计算的角度出发，对荧光增强的预测进行研究。研究在不同金属微纳结构中，态密度的改变，从而考虑对增强效果的影响。通过修正的模型描述不同金属的介电特性，研究不同微纳结构和金属类别情况下荧光增强的特性。通过考虑探针分子与金属表面的相互作用，更精确搭建表面增强的理论模型。首先，研究了在不同金属表面结构下荧光的增强效果。其次，利用量子化的方法，研究荧光探针的辐射与不同电场的耦合相互作用。本项目对深入理解表面荧光增强的物理机制、推广荧光技术的应用范围具有重要意义。