Abstract

In this paper we investigate the importance of electron-electron scattering for the relaxation of the electrons to the lattice temperature in silver particles embedded in a glass matrix. Their dielectric properties allow us to clearly distinguish between the electron dynamics in the spectral region of the plasmon mode and the region of the interband transitions from the filled d band to the Fermi level. Therefore, it allows us to avoid a direct probe of the populations near the Fermi sea. It is shown that the therinalization dynamics are slower at the resonance for high excitation densities, an effect that disappears when the regimen of excitation corresponds to less than one photon per nanoparticle. In order to separate the contributions from the real and imaginary parts of the dielectric function of silver, detailed dynamical measurements have also been performed in silver thin films. These observations ' are analyzed in the context of a time-dependent random-phase approximation (RPA) dielectric function. The model takes into account an effective damping γ_eff associated to the electron-surface scattering and a collision damping γ_ee associated to electron-electron scattering.

© 1998 Optical Society of America