金芯-银壳复合纳米微粒光学吸收光谱分析

通过液相还原法制备出金．银复合纳米颗粒。透射电镜图像显示所制备金-银复合纳米颗粒呈球状的芯-壳结构。光学吸收谱的实验表明：金芯．银壳复合结构纳米微粒具有双峰的等离子体吸收带。一个峰值的波长位于纯银纳米颗粒的等离子体吸收带附近；另一个介于纯银和纯金纳米颗粒的等离子体吸收峰之间，且随着反应试样中银的摩尔分数的增加发生蓝移，基于实验分析和Mie散射理论的定量计算。结果认为：该吸收峰的蓝移可归因于银壳层厚度的增加。

Analysis of Optical Absorption Spectra ofAg-Coated Au Composite Nanoparticles

Ag-coated Au composite nanoparticles are prepared via solution-phase reduction method and clearly observed by TEM. The optical absorption spectra show that the as-prepared particles have two distinct plasma a absorption bands. One absorption peak centers near the plasma a absorption band of pure Ag nanoparticles, another absorption peak intervenes between the plasma a absorption bands of pure Ag and pure Au nanoparticles and undergoes blue-shift. According to the experimental analysis and numerical calculation based on Mie scattering theory, it is reasonable to attribute the blue-shift to the thickness increasing of Ag-shells.