Absolute intensities in the ν₁, 2ν₂, 2ν₃ + ν₄ band system of carbonyl fluoride

Abstract

The IR spectrum of carbonyl fluoride, COF₂, has been measured in the region 1880–1980 cm⁻¹ using a Bomem Fourier transform spectrometer under 0.005 cm⁻¹ resolution at a gas pressure of 3.2 Torr, 10 cm pathlength and at room- and stratospheric (ca. 200 K) temperatures. In this region the ν₁ band at 1945 cm⁻¹ dominates the spectrum and is in Fermi resonance with the weaker 2ν₂ band at 1914 cm⁻¹, and in B-type Coriolis resonance with the 2ν₃ + ν₄ band at 1936 cm⁻¹. The absorption coefficients of this band system have been determined from the experimental spectra and the integrated intensity in this region is found to be 3.07 × 10⁻¹⁷ cm molecule⁻¹ at room temperature and 3.26 × 10⁻¹⁷ cm molecule⁻¹ at ca. 200 K. Using calculated spectra the integrated intensities were predicted to be 2.90 × 10⁻¹⁷ cm molecule⁻¹ and 3.01 × 10⁻¹⁷ cm molecule⁻¹, respectively using transition dipole moments of 0.1592 D for ν₁ and 0.1097 D for 2ν₂.† The small discrepancy in integrated intensity can be accounted for from thermally populated states, whose contribution was not calculated.