Surface plasmon dynamics in silver nanoparticles studied by femtosecond time-resolved photoemission

Multiphoton photoelectron spectroscopy reveals the multiple excitation of t he surface plasmon in silver nanoparticles on graphite. Resonant excitation of the surface plasmon with 400 nm femtosecond radiation allows one to dis tinguish between photoemission from the nanoparticles and the substrate. Tw o different previously unobserved decay channels of the collective excitati on have been identified, namely, decay into one or several single-particle excitations.