Resonance Conditions for Multipole Plasmon Excitations in Noble Metal Nanorods

A resonance condition has been obtained for the position of plasmon peaks of any multipole order in the extinction spectra of silver and gold nanorods, as a function of their material, size, shape, and dielectric environment. The expression has been derived combining electrodynamics simulations with the aid of a nanoantenna-standing wave model approach. Some scaling laws, emerging from the above expression, are also demonstrated, in very good agreement with recent experiments and theoretical studies.