Fig. 1

Schematic representation of the eccentric nanoshell structures. a Schematic representation of the simulated eccentric nanoshells with the core offset a distance d from the center of the shell. R ₀ and R ₁ represent the core and shell radii, respectively. b Energy level diagram representing the plasmon hybridization in the eccentric metallic nanoshells, resulting from the interaction of the sphere and the cavity plasmons. The green dashed lines illustrate the hybridization of sphere and cavity plasmons in a concentric nanoshell. For an eccentric nanoshell, there exists an interaction between primitive plasmon modes of all multipolar order (red dashed lines). This results in an extra shift for the eccentric nanoshell of the dipolar bonding and antibonding plasmons to the red and blue, respectively (represented by the arrows of the corresponding color)