Vibrational Spectra of Gaseous 1,1,1-Trifluoro-2-butyne

Abstract

The infrared and Raman spectra of gaseous CH3C≡CCF3 have been recorded and all of the fundamental frequencies have been identified. A normal coordinate analysis indicates appreciable mixing among the symmetric CF3 vibrations and the C–C stretchings. The values of the Coriolis coefficients, ζ 9 and ζ 10 , are consistent with those of a freely rotating methyl group. Strong Coriolis coupling has been suggested as the cause for the sharp doublet contour of the ν 16 band in the Raman spectrum. The high intensities of some combination and overtone bands are explained in terms of Fermi resonance with fundamental levels. Thermodynamic functions at several temperatures have been determined in the rigid‐rotor harmonic‐oscillator approximation.