Absorption of far-infrared radiation by random metal particle composites

Abstract

Measurements have been made of the absorption of far-infrared radiation by Pd small particles randomly embedded in KCl. The small particle specimens had Pd volume fractions between 0.001 and 0.1. At volume fractions of 0.03 and below, the absorption coefficient was proportional to the Pd concentration. The frequency dependence of the absorption coefficient was typically quadratic below 30 ${\mathrm{cm}}^{-1\mathrm{}}$ with a slower dependence above 30 ${\mathrm{cm}}^{-1\mathrm{}}$. The absorption coefficients were about a factor of 10 larger than those calculated from a theory based on electric and magnetic dipole absorption.