金银三层纳米管局域表面等离激元共振特性研究

相对于单一金属纳米材料,二金属复合纳米材料具有更大的潜在应用价值.基于时域有限差分方法,研究了SiO₂-Ag-Au和SiO₂-Au-Ag二金属三层纳米管的消光光谱,并对其局域表面等离激元共振(Localized Surface Plasmon Resonance,LSPR)特性进行了分析.研究发现,内核尺寸变大将导致上述两种金属纳米管LSPR峰红移;内层金属及外层金属壳层厚度增大均会导致其LSPR峰蓝移.银壳厚度变化对纳米管LSPR的调制作用大于金壳厚度变化造成的影响.上述现象可以利用等离激元杂化理论及自由电子和振荡电子变化的竞争机制进行分析.

Study on the localized surface plasmon resonance properties of bimetallic gold and silver three-layered nanotubes

The localized surface plasmon resonance (LSPR) properties of bimetallic gold and silver three-layered nanotubes such as SiO₂-Ag-Au and SiO₂-Au-Ag nanotubes have been investigated with the variations of Au or Ag shell thickness and size of the core by means of Finite Difference Time Domain (FDTD) method. With increase in the core size, it is found that the LSPR peaks show red-shift. We also observe with increasing the thickness of the Au or Ag shell that the LSPR peaks show blue-shift. Furthermore, the modulation of LSPR due to Ag shell is more significant compared with that due to Au shell. We have ascribed the variations of the LSPR peaks to the plasmon hybridization and the competition between the changes of conduction and oscillation electrons.