论文部分内容阅读
提出了一种在银层上面覆盖一层金的四棱台复合纳米结构。采用离散偶极子近似(DDA)方法,针对光激发复合金属纳米粒子的局域表面等离子体共振(LSPR)进行研究,讨论了四棱台纳米粒子金银复合结构在不同尺寸、不同混合比等条件下的消光特性及折射率灵敏度。计算结果显示,在银层厚度为50 nm的四棱台纳米粒子上覆盖金层,其折射率灵敏度不变。同时,四棱台银纳米粒子厚度的增加会使其消光峰值波长蓝移。金材料比例的增加会使金银复合纳米结构的消光峰值波长红移。当金银复合结构的纳米粒子的厚度大于自由电子的平均自由程时,其局域表面等离子体激发强度不发生变化。
A tetrahedron composite nanostructure covered with a layer of gold on the silver layer was proposed. The local surface plasmon resonance (LSPR) of photoexcited composite metal nanoparticles was studied by the discrete dipole approximation (DDA) method. The effects of the four-ridged nanoparticle silver-silver composite structures on the surface morphology, Extinction characteristics under the conditions and refractive index sensitivity. The calculated results show that the refractive index sensitivity does not change when the gold layer is coated on the nano-prismatic nanoparticles with a silver layer thickness of 50 nm. At the same time, the increase of the thickness of the silver-silicon tetrahedron silver nanoparticles causes the peak extinction peak wavelength to shift blue. The increase of the proportion of gold material will red shift the extinction peak wavelength of gold-silver composite nanostructures. When the thickness of the gold-silver composite nanoparticles is larger than the mean free path of free electrons, the local surface plasmon excitation intensity does not change.