Femtosecond decay-time measurement of electron-plasma oscillation in nanolithographically designed silver particles

Abstract.

The decay time of the electron-plasma oscillation in silver nanoparticles is measured at a nanoparticle film consisting of regularly arranged, identically shaped and identically oriented particles. By design of a noncentrosymmetric particle shape, SHG in transmission at normal incidence of the fundamental beam is obtained. Therefore the autocorrelation function of the optical near field oscillation of the particle, excited by two emporally overlapping fs laser pulses separated by a defined delay time, could be measured. A decay time of 10¹ fs was extracted. This result shows that the damping of the electron-plasma oscillation in nanometric particles is approximately a factor of 2 larger than expected from the value of the imaginary part of the bulk metal dielectric funtion when consideration of the radiation damping in the particles is included.