染料分子吸附在正、负电性纳米银上的荧光增强及荧光猝灭现象

Quenching and Enhancement of Fluorescence of Dye Molecule on Negative and Positive Colloid Silver Particles

制备了两种不同表面电性的胶态纳米银 ,选取阴离子型染料分子荧光素钠、既有阴离子基团又有阳离子的染料分子罗丹明B ,研究其在两种纳米银表面的荧光增强及荧光猝灭现象 .当罗丹明B(RhB)分子分别吸附在这两种纳米银上时 ,对负电性纳米银 ,观察到荧光猝灭、荧光峰红移现象 ,且在分子的浓度适当时 ,加入KBr可获得较强的表面增强拉曼光谱 ;在正电性纳米银上 ,当分子的浓度较大时观察到荧光猝灭 ,当分子的浓度较小时观察到荧光增强 .而当荧光素钠分子 (FS)分别吸附在这两种纳米银上时 ,在负电性纳米银 ,观察到荧光猝灭 ;在正电性纳米银上观察荧光急剧增强现象 .从分子的结构及纳米银表面局域场增强或无辐射通道的增加对增强和猝灭的原因作了讨论 .

Both negatively and positively charged colloids (in brief, PCS and NCS) of silver nano-particles were prepared. Quenching and enhancement of fluorescence from rhodamine(RhB) and Fluorescein sodium(FS) molecules on the two colloids of silver nano-particles were recorded respectively and compared with each other. On PCS, the fluorescence of RhB is enhanced when the concentration is low, whilst when the concentration is high the fluorescence of RhB is quenched. However for FS, the fluorescence is always enhanced. On NCS, the fluorescence of FS and RhB are quenched.