Optoacoustic response of a single submicronic gold particle revealed by the picosecond ultrasonics technique

The optoacoustic response of a single submicron (430 nm) gold particle embedded in a silica thin film is experimentally revealed by femtosecond pump-probe experiments. A semianalytical model is developed to calculate the transient reflectivity accounting for optical index changes in both media and for particle and film surface displacements. The displacement of the particle-film interface turns out to be the major contribution to the measured signal. The amplitude of the acoustical component of the transient reflectivity is modulated by the depth at which the particle is buried in the film.Etude de l'amplification de la Conduction Thermique dans des Réseaux de Nanoparticule