Investigation of resonant properties of metal core-shell nanoparticles using T-matrix calculations

Using T-matrix method, plasmon resonance properties of metal core-shell nanoparticles are systematically investigated. It is shown that dielectric/metal core-shell structure may be excited stronger at resonance than metal/dielectric and hetero-metal ones, but the resonance states are extremely sensible to the layers thickness. For three-layer nanospheres, resonance properties will be dominated by a sub-10 nm silver outermost shell, while only weakened by a silica one. Finally, tiny eccentric distance between the centers of core and shell in eccentric two-layer nanoparticles may fundamentally change the resonance mode of nanoparticles, and results in higher local electrical field enhancement than concentric nanospheres.

► Dielectric/metal core-shell structure can be excited strongest in two-layer spheres. ► Sub-10 nm metal shell may dominate the resonance property of whole three-layer sphere. ► Tiny eccentric distance can fundamentally change the resonance mode of nanoparticles. ► Hot-spots on the surface of eccentric particles are calculated with T-matrix method.