Onset of charge localisation on coupling multipolar absorption modes in supported metal particles

An experimental evidence of the local enhancement of the electric field on supported metal nanoparticles is given in the case of a silver thin film growing on alumina, as studied in situ by surface differential reflectance. The dynamic charge localisation is driven by the inter-particle coupling of the multipolar plasmon absorption modes. Those modes and the associated polarisation charges are assigned via the modeling of the optical response.