金银三层纳米管局域表面等离激元共振特性研究
Study on the localized surface plasmon resonance properties of bimetallic gold and silver three-layered nanotubes
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摘要: 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SiO_2-Ag-Au和SiO_2-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 suIrfaceplasmon 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.Abstract: The localized surface plasmon resonance(LSPR) properties of bimetallic gold and silver three-layered nanotubes such as SiO_2-Ag -Au and SiO2-Au-Ag nanotubes are investigated by means of finite difference time domain method with varying the Au or Ag shell thickness and the size of the core.With the increase in core size,it is found that the LSPR peaks are red shifted.We also observe that the LSPR peaks blue shifted with the increase of thickness of the Au or Ag shell.Furthermore,the modulation of LSPR due to Ag shell is more significant than due to Au shell.We ascribe the shifts of the LSPR peaks to the plasmon hybridization and the competition between the free electrons and the oscillation electrons.
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