椭圆截面金纳米管的局域表面等离激元共振特性研究

基于时域有限差分方法研究了几何形状、入射电场偏振方向、管壁厚度及内核和包埋介质的变化对椭圆截面金纳米管局域表面等离激元共振特性的影响.研究发现,当长轴固定时,短轴的减小将导致纳米管消光峰红移;入射电场偏振方向与椭圆长轴夹角的增大将导致消光峰红移;当颗粒整体尺寸不变时,管壁厚度减小同样会使得消光峰红移.此外,内核及包埋介质介电常数的增大均导致消光峰红移.利用等离激元杂化理论及自由电子和振荡电子竞争机理对上述现象进行了理论分析. 关键词： 消光光谱 局域表面等离激元共振 金纳米管 时域有限差分方法

Localized surface plasmon resonance properties of elliptical gold nanotubes

The effects of ellipse shape, polarization direction of incident light, shell thickness, and dielectric constants of core and embedding medium on the localized surface plasmon resonance (LSPR) of elliptical gold nanotube have been investigated by the Finite Difference Time Domain (FDTD) method. When the semimajor axis is fixed, it is found that with the increase of the semiminor axis of the ellipse the extinction peak of the gold nanotube has a red-shift. With the increase of the angle between the incident polarization and the semimajor axis, the extinction peak has a red-shift. With the shell thickness decreasing, the extinction peak of gold nanotube also has a red-shift. Furthermore, we also find that the increase of the dielectric constant for core or embedding medium will induce a red-shift of LSPR in gold nanotube. The change of the extinction peak is ascribed to the plasmon hybridization and the competition between the variations of conduction and oscillation electrons.