7. Optical properties of metal nanoparticles

The optical properties of metallic nanoparticles are dominated by the collective excitation of conduction electrons resulting from interaction with electromagnetic radiation. These properties are observed in gold, silver and copper particles, due to the presence of conduction electrons. The electric field of the incident radiation creates an electric dipole in the particle. To compensate for this effect, a force is created in the nanoparticle at a unique resonant frequency.