局域表面等离激元增强荧光研究进展

Advances in localized surface plasmon enhanced fluorescence

金属表面增强荧光现象,即表面等离激元与荧光分子、原子、量子点等发光体系的相互作用,是许多应用研究的基础科学问题.近年来该领域在实验和理论方面都取得了很大的进展.研究表明,金属表面等离激元共振不仅能够增强分子的激发过程,也能强烈地调制分子荧光的发射过程,如影响发光的量子效率、弛豫寿命和发射方向等.通过设计微纳金属结构,局域表面等离激元可以有效地改变分子所处的介电局域电磁场环境,进而影响和调控荧光分子的自发辐射过程.实验研究从初始的集体平均性观测,目前已经发展至单纳米结构和单分子水平,从而克服了传统测量中的平均效应,并做到实验测量和理论模拟的有机结合,对揭示单个纳米颗粒层次上的光物理基本规律具有重要意义.本文主要介绍近期与局域表面等离激元增强荧光相关的重要研究进展,具体为表面增强荧光的发光强度、光发射角分布、荧光光谱、荧光弛豫寿命及偏振等方面.

Metal surface enhanced fluorescence is a kind of light-matter interaction importantly, i.e., the interaction of surface plasmon resonance and light emitters like as fluorescence molecule, atoms, and quantum dots etc. This interaction with great progress being made recently is a fundamental problem for many potential application fields. The surface plasmon resonance can concentrate the light to strongly enhance the excitation process, furthermore, the emission process is also modulated by the plasmonic nanostructures presenting a modified quantum yield, fluorescence decay lifetime, and emission directivity. That is to say, the electromagnetic environment of the emitters can be engineered through designing specific metal nanostructures, and then the spontaneous emission process becomes to be controllable at the nanoscale. Nowadays, the state-of-the-art experimental method allows us to investigate the surface enhanced fluorescence at single nano-objects and single molecule level at which the theoretical method can meet with the experiments well. In this review, some representative advances related to localized surface plasmon resonance enhanced fluorescence would be presented, specifically, the properties about surface enhancement intensity, emission directivity, fluorescence spectral shape, fluorescence lifetime and emission polarization etc in surface enhanced fluorescence would be discussed in detail.