不同表面修饰和尺寸的纳米银的荧光增强效应的研究

分别以柠檬酸钠(CTS)和聚乙烯吡咯烷酮(PVP)为表面修饰剂，采用化学法制备纳米银(分别标记为Ag-CTS和Ag-PVP)。当甲基橙溶液中加入Ag-CTS或Ag-PVP时，S₂→S₀和S₁→S₀荧光强度分别明显减弱和增强。不同的是Ag-PVP引起S₂→S₀和S₁→S₀荧光强度减弱和增强的幅度更大，且S₂→S₀荧光峰出现红移。当甲基橙溶液中加入Ag-CTS时，S₁→S₀荧光强度随时间延长逐渐增强，而加入Ag-PVP时，S₁→S₀荧光强度则不随时间而变化。颗粒尺寸较大的片状结构纳米银引起S₁→S₀荧光强度增强比率较小。甲基橙溶液浓度越低，S₁→S₀荧光强度增强比率越大。研究结果表明，纳米银表面吸附的不同表面修饰剂通过影响纳米银与甲基橙分子间距离进而影响纳米银的荧光增强效应;纳米银尺寸大小则由于所产生的局域面表面等离子共振特点等差异影响其局域场增强效应。

Fluorescence Enhancement Effect of Silver Nanoparticles with Different Surface Modifiers and Sizes

Silver nanoparticles were prepared by chemical method using citricacid trisodiumsalt (Ag-CTS) and polyvinylpyrrolidone (Ag-PVP) as surface modifiers, respectively. When Ag-CTS or Ag-PVP nanoparticles were added into methyl orange (MO) solution, the enhanced-fluorescence of S₁→S₀ and quenched-fluorescence of S₂→S₀ were simultaneously observed. However, for the solution containing Ag-PVP, the red-shift of fluorescence peak of S₁→S₀ was observed and the extents of the enhanced-fluorescence of S₁→S₀ and quenched-fluorescence of S₂→S₀ are higher than those of the solution containing Ag-CTS. With the increase in reaction time the fluorescence intensity of S₁→S₀ increased gradually in the solution containing Ag-CTS nanoparticles and no change was observed in the solution containing Ag-PVP nanoparticles. The lower the MO concentration, the higher the fluorescence intensity ratio of S₁→S₀. The results indicated that the silver nanoparticles with different surface modifiers affect the metal-enhanced fluorescence by impacting the distance between the methyl orange and silver nanoparticles. The size of silver nanoparticles affects the metal-enhanced fluorescence due to the difference in the surface plasma resonance properties.