金属纳米结构的形状对其消光特性的影响研究

Influences of Shape on Extinction Spectrum for Metal Nanoparticles

推导了任意形状金属纳米结构的局域表面等离子体共振波长的解析解,分析了金属纳米结构的形状对其消光特性的影响。计算与分析结果表明,在空气中(折射率n=1.0),某种金属的纳米结构的消光光谱谐振波长仅与形状有关,形状参数L可以拟合为宽高比的二次函数,且二次项的系数代表了金属纳米结构的尖锐程度,形状越尖锐,谐振波长便越长。共振波长的研究对根据需要合理设计金属纳米结构具有重要的指导意义。

An analytical solution is presented to describe the plasmon resonant wavelength of nanoparticles with arbitrary shapes. Calculation and analysis results demonstrate that the peak wavelength of the extinction spectrum for a nanoparticle of a certain material is determined by the shape parameter L only. The shape parameter L is in good fitting with a quadratic function of aspect ratio η,and its quadratic term coefficient a is a parameter that describes the acutance of a nanoparticle： the sharper nanoparticle is,the larger a is,and as a result,the longer the peak wavelength will be. This investigation can be used as a guideline in designing nanostructures for certain applications.