We investigate optical properties of the deterministic network model for fr
actal metallic clusters at the percolation threshold. As input data we used
the experimental bulk dielectric function of gold, aluminum, and nickel. S
harp absorption resonances in the optical spectra are observed only for gol
d. They are pronounced only for clusters consisting of particles with sizes
larger than the mean free path of the conduction electrons. In smaller par
ticles the peaks are heavily damped due to scattering of electrons by the p
article surfaces. (C) 2001 American Institute of Physics.