OPTICALLY INDUCED DAMPING OF THE SURFACE-PLASMON RESONANCE IN GOLD COLLOIDS

The surface plasmon damping induced by high excitation of the electron gas is studied in femtosecond pump-and-probe experiments on gold coll oids embedded in a sol-gel matrix. Optical excitation of single-partic le interband transitions leads to a pronounced broadening of the surfa ce plasmon line. A similar behavior is observed For resonant excitatio n of the surface plasmon. This broadening is the dominant optical nonl inearity of the system, and reflects the excitation-induced damping of the surface plasmon resonance. The time evolution of the damping rate follows that of the electronic scattering rate.