中文摘要：

当电子振动频率与入射光的频率相同时,部分金属纳米颗粒可以在其表面激发局部表面等离子共振效应（LSPR）,该波长下颗粒的吸收增强。这种效应也被应用于增强拉曼光谱信号的强度。本文研究了以Ag为外壳材料、Si为内核的核壳结构纳米颗粒粒子系的吸收特性。采用时域有限差分方法求解了颗粒随机分布粒子系的吸收率,分析了颗粒体积分数、内核外壳尺寸、椭球化等因素对粒子系吸收特性的影响以及对吸收峰的调控作用。

英文摘要：

Localized surface plasmon resonance（LSPR）can be excited on metal nanoparticles.The LSPR occurs when the oscillation frequency of electrons is equal to that of the incident light.At this frequency,the absorption of metal nanoparticles can be strengthened.The LSPR effect has been applied to the surface-enhanced Raman scattering（SERS）.In this study,absorption of Ag-Si core-shell nanoparticle clouds is investigated.The finite-difference time-domain method is applied to obtain the absorption of particulate media,with core-shell nanoparticle randomly distributed.Effects of particle volume fraction,core and shell radii,spherical and ellipsoidal shapes are analyzed.Tuning of absorption peaks by different factors is also discussed.