Shift fashion of surface plasmon resonances in non-spherical gold nanoparticles: A simple model of surface plasmon dynamics

A simple and efficient dynamic model of oscillatory surface electrons under coulombic attraction is developed to illuminate the mechanism of split and shift fashion of surface plasmon resonance (SPR) in non-spherical symmetric gold nanoparticles. In this model, the oscillatory electron cloud has been simplified into a charged mass point. So the geometrical factors of the particle are introduced to the dynamic equation. And then the analytical expressions for SPR frequency dependence on aspect ratio of both gold nanorod and nanoprism are obtained. These shift fashions of SPR are in agreement with the experimental data and quasi-static simulations results. This simple and intuitive picture can also be used to understand the plasmon resonance behavior of asymmetric metallic nanostructures of greater geometrical complexity and to guide the design of metallic nanostructures and predict their SPR properties.