金属Ag包覆介质球的FCC结构反射特性研究

Reflectivity Behavior of Silver Nanoparticle Coated Spheres in FCC

用转移矩阵方法研究了由核壳(Core-Shell)结构组成的面心立方在可见光和近红外波频域的反射特性.考虑金属介质的色散特性,计算了壳层厚度对禁带的影响及沿与ΓL方向成一定角度θ时的反射特性曲线.研究发现,当包覆层厚度d小于0.08倍的这种核壳结构的半径时,随d增大低频域第一反射峰的位置"蓝移";并且金属厚度大于该阈值时基本无变化.而在同一包覆层厚度,随入射角度θ增大低频域的第一反射峰逐渐"蓝移";在θ=40°时第二反射峰突变.

The light reflectance of opals, coated with silver nanoparticle spheres in the optical and near infrared frequency range,were studied by transfer-matrix method. With regard to the dispersion feature of metal, the effect which the shell＇s thickness causes to the band gap and the reflectivity of different incidence angles which were apart from FL,calculated using the Drude Model. A small increment of thickness leads to a blueshift of the first reflectance peak when the thickness of the coating is less than 0.08R, but a larger thickness only leads to a tiny excursion of position of the reflectance peak. Increasing angle θ at the same coating thickness can illustrates a gradual blueshift of the first reflectance peak in low frequency regions. The second reflectance peak shows a sharp mutation when the angle θ is 40°.