Far Infrared Spectrum and the Barrier to Internal Rotation in 1,1,1,2-Tetrafluoroethane

Abstract

The spectrum of 1,1,1,2-tetrafluoroethane gas has been examined in the far infrared (50–420 cm—1). Bands were observed at 120, 225, 350, and 409 cm—1. The contour of the strong band at 120 cm—1 is consistent with that to be expected for the torsional oscillation. This frequency would correspond to a triple cosine barrier of 4.2 kcal/mole.