纳米银与表面吸附荧光素的荧光性能的影响

研究了纳米银粒子对表面吸附荧光素(fluorescein,Fl)的荧光性能的影响。Fl溶液中加入纳米银粒子，Fl分子包覆在纳米银粒子表面形成Fl_n-Ag复合物使纳米银相互桥连形成类似网络的结构，且Fl分子吸收峰随着纳米银浓度的增加发生红移。纳米银通过产生的强局域场将能量传输给Fl发光中心，实现了Fl的荧光增强，荧光增强效率随着纳米银浓度的增加具有最大值。较大粒径的纳米银使Fl获得最大荧光增强效率所需浓度较低且最大荧光增强效率值较高。研究结果表明，纳米银与Fl间的能量传输主要由Fl分子附近局域电磁场增强和分子到金属表面无辐射跃迁能量转移过程所决定并与纳米银的浓度、尺寸密切相关。

Effects of Silver Nanoparticles on Fluorescent Properties of Fluorescein

The effects of silver nanoparticles on the fluorescent properties of the fluorescein in aqueous solution were investigated in the present paper.The fluorescein-coated silver nanoparticles form Fln-Ag complexes,leading to a netlike structure among silver nanoparticles.The fluorescent intensity of the fluorescein was enhanced due to the energy transfer from silver nanoparticles to fluorescein owing to the local field enhancement brought by the surface plasmon resonance of silver nanoparticles.Furthermore,with the increase in silver nanoparticle concentrations the fluorescence enhancement efficiency has a maximum.The larger-size silver nanoparticles have a maximum enhancement efficiency in the lower concentration region.The energy transfer between the fluorescein and silver nanoparticles depends on the local field enhancement around the fluorescein, the nonradiative energy transfer,the silver nanoparticles concentration and size.