Infrared Intensities and Bond Moments in Formaldehyde

The infrared band intensities of formaldehyde have been measured in the gas phase using the pressure broadening method. From the results of the normal coordinate analysis and the experimental intensities, the bond moments and their derivatives have been calculated for the three symmetry species. The relative signs of ∂μ/∂Q5 and ∂μ/∂Q6 have been determined from the investigation of the Coriolis interaction between ν5 and ν6. The results chosen from the calculations are: μCH = 0.5D (C——H+), (∂μ/∂r)CH = 1.3×10—10 esu, μCO = 1.9D (C+—O—), (∂μ/∂r)CO = —1.9×10—10 esu. The B1 symmetry block gave an abnormally large μCH of about 1D.