利用离散偶极近似(Discrete Dipole Approximation-DDA)算法, 从理论上模拟分析了金银核壳结构复合纳米颗粒的消光光谱以及不同核壳厚度、不同介质折射率情况下峰位的变化情况。研究结果表明, 随着壳层厚度的增加, 复合纳米颗粒的消光谱线先逐渐形成两个与单质金属纳米颗粒相似的消光峰, 后又逐渐合为一个半峰宽度较宽的消光峰;在不同介质环境中复合纳米颗粒的消光峰都随着介电常数的增大出现红移;无论是作为核层还是壳层, 银对总体消光谱线的作用都要比金强。

Based on the discrete dipole approximation (DDA) method, we studied the extinction properties of gold and silver core-shell composite nanoparticles and the change of peak position with different core-shell size and dielectric environment. The results display that with the increase of shell thickness, the extinction spectra of composite nanoparticles changes from two peaks as formed by two elemental metal to one peak with a wider half-peak width. With the increase of the permittivity of dielectric environment, the extinction peaks take place to a redshift. And whether as core or shell, silver has a stronger contribution to the extinction spectra than gold.