Ultrashort Surface-Plasmon and Phonon Dynamics

Abstract

We have studied the excitation and decay of surface plasmons at a silver-air interface using a time-resolved optical technique. Monitoring the surface-plasmon propagation enabled us to measure the dephasing of surface plasmons via their mean free path and a momentum lifetime of 48 fs (13 \ensuremath{\mu}m) was found. After a very rapid plasmon decay the energy is transferred into a strain wave and an increase in the temperature of the silver film. We have observed the acoustic phonons, associated with the strain, bouncing up and down the silver film and the heat diffusion on a picosecond time scale.