Energy Absorption in Gold Nanoshells

A modeling study on energy absorption and transport in an isolated nanoshell and aggregates of nanoshells under localized surface plasma resonance (SPR) conditions is presented. A comprehensive model for multi-scattering of electromagnetic waves by a cluster of multilayered nanoshells is developed, which applies the Wigner-Eckart theorem for the calculation of the total scattering cross sessions of nanoshell aggregates. Absorption by an isolated nanoshell and by nanoshell clusters is studied using the model. Results show that the inter-nanoshell coupling results in strong field enhancement near the particle surface. Energy absorption in a nanoshell can be tuned by varying the structural parameters of the nanoshell. Smaller particles are more absorbing than the large ones, other conditions being equal. Because of the presence of a dielectric cavity, the radial distribution of the absorbed power in the metal shell may differ from the classical skin depth phenomena. The interaction among particles in close proximity causes the energy absorption efficiency and the resonance position of a nanoshell cluster to differ from those of an isolated nanoshell.