微乳液法制备纳米银粒子的结构及其荧光现象研究

采用微乳液法合成了不同粒径的纳米银粒子,考察了环己烷和甲苯作为油相对制备纳米银的影响.对纳米银粒子的尺寸与结构进行了表征,观察到近球形多晶粒子,并有孪晶结构存在,对晶体结构的分析表明银粒子存在不同程度的点阵畸变,晶面间距增大.不同粒径的纳米银粒子氯仿体系可呈现荧光光谱,而纳米银甲苯体系则无荧光发射.结合紫外—可见吸收光谱和电子自旋共振谱对该体系的荧光发射机理进行了分析 关键词： 微乳液 纳米银粒子 纳米晶结构 荧光

Studies on silver nanoparticles synthesized by microemulsion and their fluorescence

Silver nanoparticles with different diameters were synthesized by microemulsion method, in which the effect of toluene or cyclohexane as an oil phase on the particle size and its distribution was detected. Silver nanoparticles were near spherical, both multicrystals and twins were observed. Lattice deformations existed in different degrees because the interplanar space d was increased. The fluorescence spectra for different size silver nanoparticles dispersed in organic solvents were measured. There are three emission peaks for silver nanoparticles/chloroform systems, while no fluorescence emission was found when silver nanoparticles dispersed in toluene. The fluorescence intensity varies with particle size of the silver nanoparticles, which originates from Ag 2, Ag 3 clusters on the silver particle surface produced by the interaction between silver and chloroform under UV radiation. The reactivity and the number of surface reactive centers vary with silver particle size, resulting in the different fluorescence phenomena.