THE DIELECTRIC BEHAVIOR AT LOW TEMPERATURES OF SEVERAL GASES ADSORBED UPON POROUS VYCOR GLASS

Abstract

The complex dielectric constants of several systems comprising a gas adsorbed on Vycor glass have been measured at temperatures between 0 °C and −180 °C and frequencies between 3 kc/sec and 4 Mc/sec. The real and imaginary parts of the dielectric constant of the adsorbed phase have been computed. Loss maxima occurring at low temperatures are observed for some of the matter in the monolayer and are assumed to be due to complexes formed between the gas first admitted and hydroxyl groups which are covalently attached to the surface of the glass. The complexes may be considered either as dipoles having two equilibrium positions, or as highly damped oscillators. Ethyl chloride adsorbed in the first molecular layer and not bonded to OH behaves as an oscillatory system for which no loss is observed in the frequency and temperature ranges studied. Ethyl chloride adsorbed in the multilayers behaves similarly but shows a slightly greater temperature coefficient of ε′. Both these types of adsorbed ethyl chloride interact with the complexes and reduce the threshold temperature at which loss is observed in the complex. Methyl chloride interacts with OH groups in a similar fashion, but n-butane does not.