纳米银对表面吸附荧光素的荧光增强和荧光猝灭效应及KCl的荧光猝灭释放效应

制备了两种不同粒径的纳米银溶胶，研究了在水溶液条件下其对表面吸附荧光素(FL)的荧光性能的影响及KCl电解质对该体系荧光性能的影响。FL溶液中加入纳米银，FL分子吸收峰位发生红移。随着纳米银浓度的增加，FL分子荧光先出现增强，而后又逐渐猝灭。粒径较大的纳米银产生最大荧光增强比率所需浓度较低。在纳米银猝灭FL分子荧光的溶液中加入KCl电解质，随着KCl浓度的增加，荧光逐渐增强，出现了荧光猝灭释放效应。研究结果表明，纳米银对表面吸附FL的荧光作用与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决定并与纳米银的浓度、尺寸及电解质等密切相关。

Enhancing and Quenching Effect of Silver Nanoparticles on the Fluorescein Fluorescenc and Quenching Release by KCl

Two kinds of silver nanoparticles with different size were prepared. Fluorescent properties of fluorescein in the presence of silver nanoparticles and KCl electrolyte concentration were studied. The absorption peak of FL was red shifted when silver nanoparticles were added. Furthermore, with the increasing in silver nanoparticles concentration, the fluorescence increases first and then decreases. The larger silver nanoparticles have maximum enhancement ratio in lower concentration region. The addition of KCl can promote enhancement of fluorescence and show quenching release effect. The results suggest that the effect of metal-enhanced fluorescence is strongly affected by the local field enhancement, the size and concentration of silver nanoparticles and electrolyte.