Near-Field Optical Detection of Plasmon Resonance from Gold Nanoparticles: Theoretical and Experimental Evidence

The study of plasmon-induced electromagneticfields is a very interesting topic for basic research and photonicapplications. The plasmon properties depend on manyfactors, such as composition, size, shape and arrangement ofnanoparticles. In this paper, we propose an experimental andtheoretical study on the optical properties of gold nanoparticlesdeposited by pulsed laser ablation and investigated bynear-field optical microscopy (SNOM) in a transmission farfieldcollection scheme. The electromagnetic field propertieshave been simulated by an exact theoretical analysis based onthe multipolar expansion of the fields and on T-matrix approach.The theoretical model almost accurately reproducesthe experimental data and makes us confident that the usedmethod is suitable to describe more complex system of metalnanoparticles.