Metallic nanoparticles detected by infrared spectroscopy

Small Ni, Cu, Fe, Ag, Pt, Au nanoparticles with average diameters in the nanometer range have been studied by infrared spectroscopy. The Ni, Cu, Fe, Ag, Au nanoparticles were embedded in transparent matrices, AlN or Si(3)N(4), or deposited on Si(3)N(4) in the case of Pt. They were previously characterized by several techniques such as X-ray absorption spectroscopy, grazing incidence small-angle X-ray scattering or transmission electron microscopy. Infrared absorption depending on the metal is detected in the 60meV to 140meV energy range. It is interpreted as due to low-energy collective electron excitations related to the 2D confinement occurring at the metal-matrix interface. Copyright (C) EPLA, 2008.