Infrared Intensities and Bond Moments in Formaldehyde

Abstract

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: μ_CH = 0.5D (C^——H⁺), (∂μ/∂r)_CH = 1.3×10^—10 esu, μ_CO = 1.9D (C⁺—O^—), (∂μ/∂r)_CO = —1.9×10^—10 esu. The B₁ symmetry block gave an abnormally large μ_CH of about 1D.