By means of discrete dipole approximation theory, the extinction properties in the range of UV-Vis-NIR of spherical silver nanoparticles and silica/silver nanoshells were simulated. The simulation results display that with the increase of diameters of spherical silver nanoparticles, the dipole extinction peaks gradually redshift, the quadrupole extinction peaks begin to appear and then inchmeal redshift, and scattering efficiency exceeds absorption efficiency. Size and core-shell ratio of silica/silver nanoshells have great influences on extinction property, namely, with the increase of core-shell ratio the main extinction peaks take place to redshift regularly, and with same core-shell ratio the extinction peak of larger nanoshell is located at longer wavelength. When the silver shell thickness is greater than electronic mean free path of silver, the extinction performance of nanoshells is consistent with that of same-sized silver nanoparticles.%采用离散偶极近似理论,对球形银纳米颗粒和氧化硅/银纳米壳层在紫外-可见-近红外波段的消光性能进行模拟计算研究.研究结果表明:随着粒径的增加球形银纳米颗粒的偶极消光峰逐渐红移,四极消光峰开始出现且逐步红移,散射作用增强而吸收作用减弱.粒径和核壳比对氧化硅/银纳米壳层的消光性能均有很大影响,随着核壳比增大,主要消光峰发生规律性红移:当核壳比相同时,较大粒径的纳米壳层其消光峰位于较长波长处.当银壳层厚度超银的电子平均自由程时,纳米壳层的消光特征与同粒径银纳米颗粒的完全一致.
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