金属核壳结构在不同介质环境中的表面等离子体消光特性研究

本文利用Mie散射理论计算了在不同介质环境中银纳米核壳结构的表面等离子共振消光谱,研究了内核的直径、金属壳层的厚度以及周围介质折射率对表面等离子共振特性的影响,结果表明,对于内核尺寸较小的核壳结构,外界折射率的增加所导致的自由电子振荡回复力的减小,不仅会引起共振峰的红移,还会导致消光强度的增大。同时,外界折射率环境对核壳的球模式和腔模式的耦合作用影响显著,折射率越高,耦合分裂越强烈,反对称模式共振峰越明显。

Surface Plasmon Characteristics of Metal Core-sheU Structure in Different Dielectric Environments

The surface plasmon extinction spectra of Ag core-shell structures in different dielectric environments are calculated using the Mie scattering theory. The influence of core diameter, shell thickness and surrounding refractive index on the surface plasmon resonant characteristic is studied. The results show that for the core-shell with small size, the increase of refractive index induced restore force reduction of free electron oscillation will not only lead to the redshift of resonant band, but also the increase of extinction efficiency. Moreover, the surrounding dielectric environment has a strong effect on the coupling effect between inner and outer surface plasmon mode. The higher the refractive index, the stronger the coupling induce splitting and the more obvious the anti-symmetry resonant band.