金属纳米颗粒的极化率与异常光学性质

基于金属纳米材料的异常光学现象,考虑了束缚电荷作用的情况,从理论上推导出在光波照射下金属纳米颗粒的极化率与颗粒尺度关系的结果,进而得到金属颗粒对光波的吸收率,并讨论颗粒尺度对极化率和吸收率的影响,即当金属粒子尺寸达到纳米级时,将金属粒子看作纳米小球,小球极化率出现半径的立方因子,且小球半径小于电子平均自由程,电子的衰减因子受小球半径的制约.由推导结果可以得出,光吸收峰增强,并产生红移.这些结果为深入理解金属纳米颗粒的异常光学性质,揭示和开发应用金属纳米材料的性质提供理论基础.

Dynamic polarizability and abnormal optical properties of metal nanoparticles

Based on the abnormal optical phenomena of metal nano-materials and taking the action of bound charges into account, the relationship between the dynamic polarizability and the size of metal nanoparticle under the light irradiation is investigated theoretically, and the light absorptivity of the mead particle is obtained. Furthermore, the effects of the size of particle on the polarizability and absorptivity are discussed. When the size of a metal particle is close to nano-grade and the par-ticle is regarded as a small ball, the results show that the polarizability has a cubic radius factor, the ball radius is less than the electron mean free path, and the electronic damping rate depends on the ball radius. The theoretical results show that light absorption is enhanced and presents red shifts. These results provide a theoretical basis for deep understanding the abnormal optical properties of metal nanoparticles, also for the revealing and the application developing of the characters of metal nano-materials.