Au纳米粒子表面附近偶氮苯分子的吸收光谱

摘要

我们将时空间含时密度泛函理论与经典的电动力学时空间有限差分技术相结合,对吸附在Au纳米粒子表面附近的偶氮苯分子顺式和反式两种同分异构体的光学性质进行了研究.计算结果显示,一方面表面等离子激元共振会增大其周围激光外场的强度,从而使得偶氮苯分子的吸收光谱得到增强,另一方面,吸附分子与金属纳米粒子之间的相互耦合作用也会对一些低能特殊谱峰的强度及位置产生影响,从而使得谱线的形状与单独的偶氮苯分子或Au纳米粒子并不相同.此外,等离子激元的增强效应会随着分子与金属纳米粒子之间的距离以及纳米粒子尺寸的变化而发生变化.%In this paper,a real-time time-dependent density functional theory (TDDFT) coupled with the classical electrodynamics finite difference time domain (FDTD) technique is employed to investigate the optical properties of hybrid systems composed of gold nanoparticles (NPs) and the azobenzene adsorbate.The results demonstrate that the molecular absorption spectra over the entire energy range can be enhanced by localized surface plasmon resonance (LSPR) of Au NPs.However,the electronic coupling between the azobenzene and Au nanoparticles influences the energy and intensity of some special absorption peaks,leading to quite different spectral profiles of the hybrid complexes compared to those of isolated molecules or sole NPs.The plasmonic enhancement is also dependent on the NP-molecule separation distance and the geometrical parameters of NPs.