METHYL TORSIONAL MODES IN MOLECULAR SOLIDS

Abstract

The far infrared spectra of several molecular solids which contained one, two, three, and four-methyl rotors have been obtained over a range of temperatures. For the molecules which contained multiple rotors it was found for almost every case that the torsional mode which is inactive in the gas phase was always observed in the spectra of the solids. From a comparison of the frequencies for the two torsional modes a measure of the top-top interaction term for the potential energy was obtained. A comparison of the torsional barriers for a large number of one, two, and three-top molecules will be given and discussed.