Vibration Spectra and Normal Coordinate Treatment of Perfluorocyclobutane

The Raman spectra of gaseous and liquid cyclic C4F8 at room temperature have been obtained and polarization measurements made for the liquid state. The infra-red absorption spectrum of the gas between 2 and 23.1μ obtained by Dr. D. C. Smith of the Naval Research Laborotory is also reported here. A normal coordinate treatment, based on the assumption that the molecular symmetry is D4h, has been made and applied to assign the 23 fundamental vibration frequencies and to evaluate a set of force constants. The observed spectra have been interpreted in detail.