Infrared-optical properties of gas-evaporated gold blacks: Evidence for anomalous conduction on fractal structures

Abstract
We analyze infrared-optical measurements on gas-evaporated gold blacks, performed by Harris many years ago. The data agree quantitatively with recent theories for anomalous conduction on fractal structures. The frequency-dependent conductivity obeys σ∝ω0.7 below the relaxation frequency for electrons in a single particle. This is consistent with the conductivity exponents for percolation clusters and for diffusion-limited aggregates.