Embedded nanoparticles plasmon absorption

The optical properties of metal nanoparticles embedded in an insulating host differ substantially from the optical properties of bulk metals. Under the influence of an electrical field, there is a plasmon excitation of the electrons at the particle surface. This resonance, which takes place at a certain energy of the incident light, results in an optical absorption, the so-called plasmon absorption or plasma resonance absorption [1,2]. 

Noble-metal nanoparticles embedded in a dielectric medium show strong absorption peaks in the visible region of the UV-vis spectrum due to the collective motion of free electrons (surface plasmon resonance). 

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