金-银复合纳米微粒的光学吸收特性

Optical absorption properties of Au-Ag composite nanoparticles

以NaHB4做还原剂,利用一步共还原氯金酸(HAuCl4)和硝酸银(AgNO3)制备了金银复合结构的纳米颗粒。用透射电子显微镜对所制备的金银复合纳米微粒的形貌和尺寸进行了表征。紫外可见光学吸收光谱的研究表明:通过一步共还原法所制备的金银复合纳米微粒的光学吸收谱具有单峰的等离子体吸收特征,其吸收峰介于纯金和纯银纳米颗粒特征吸收峰之间,且随着反应液中金离子和银离子的摩尔比的增加而向长波方向移动。Mie散射理论的定量计算结果同样说明了实验所观察到的金银复合纳米微粒的光学吸收的组分可剪裁性。

Au-Ag composite nanoparticles were synthesized by simultaneously reduction of HAuCl4 and AgNO3 using NaHB, as reducing agent. The morphology and size of the particles were measured by the transmission electron microscopy （TEM）. UV-vis absorption spectra results show that Au-Ag composite nanoparticles prepared by the one step co-reduction method have only one plasmon absorption band. The maximum absorption peak of Au-Ag composite nanoparticles between the absorption peaks of pure gold and pure silver nanoparticles and shift towards longer wavelength with increasing the molar ratio of Au and Ag ions in the reaction solution. The numerical analysis results based on the Mie scattering theory quantitatively account for the observed optical absorption properties dependence on the composition of Au-Ag composite nanoparticles.