Optical Constants of Minerals and Other Materials from the Millimeter to the Ultraviolet

Abstract : The optical constants of a wide variety of materials were measured for this contract period. This report covers the work done at the Univ. of Missouri-Rolla. The spectral range of the measurements covered from the millimeter to the ultraviolet. The millimeter and submillimeter (far infrared) measurements were made on the Rolla Campus and the infrared, visible and ultraviolet measurements were made on the Kansas City Campus. This wide spectral range means that Kramers-Kronig analyses can be made with better precision than when reflectance data is available only over a limited spectral range. The construction of a homodyning interferometer that is capable of measuring small (diameter approximately 1 cm) samples at millimeter wavelengths and samples that are highly absorbing. To our knowledge no other instruments with this capability exist. The measurement of refractive indices of gypsum, both as a single crystal and as a powder in the far and near infrared for use as a standard. The measurement of several types of graphite. We have found that Dixon 200-10 shows a large positive real part of the dielectric constant at low frequencies. This contradicts the usual free electron picture for graphite at low frequencies.