Bond Moments and Derivatives in CF4, SiF4, and SF6 from Infrared Intensities

The absolute intensities of the fundamental infrared absorption bands of SiF4, CF4, and SF6 were measured utilizing the pressure broadening technique. The effective bond moments, μ0, and bond moment derivatives, ∂u/∂r, are calculated as a function of the most general potential constants. Based on a valence force field plus repulsion between nonbonded atoms, the most probable values (first column) and the alternatives (second column) are as follows: μ0=2.3 d 3.3 dSiF4 ∂u/∂r=−7.49 d/A 3.66 d/A μ0=1.12 d 2.36 dCF4∂u/∂r=4.88 d/A 3.35 d/A μ0=2.65 d 0.65dSF6∂u/∂r=3.85 d/A−6.58 d/AThe results are discussed.