本文采用有限元方法研究了金银合金纳米笼二聚体的光学性质。结果发现, 二聚体的吸收和散射效率对入射光的偏振方向有很强的依赖性, 当光偏振方向沿着二聚体的长轴方向时, 偶极子模式分成两个模式: 键合模式和反键合模式, 前一种模式的频带比纳米笼单体的共振频带低, 而后一种模式的频带比纳米笼单体的共振频带高。此外, 二聚体的等离子体性质还取决于两个纳米笼之间的距离, 距离越小, 等离子体模式红移越大。

The optical properties of Au-Ag nanocage dimer are analyzed using the finite element method. Our results show that the scattering and absorption efficiencies of the dimer very much depend on the polarization of the incident wave due to the surface plasmon resonance. When the polarization is along the long axis of dimer, the dipole mode of a dimer is divided into two coupling modes: the bonding and anti-bonding modes. The frequency band of the former mode is lower than that of the dipole mode of a single nanocage; in contrast, the latter is higher. Moreover, this behavior is dependent on the gap. Normally, the smaller the gap, the more red-shifted these plasmon modes are.