Infrared band intensities of formaldehyde and formaldehyde-d2

The infrared band intensities of formaldehyde and formaldehyde-d2 have been measured in the gas phase using an FT–IR spectrometer. The effect of the polymerization of the sample molecule was minimized to measure the correct intensities. When the bands overlapped each other, their individual intensities have been determined by a band simulation calculation taking account of the Coriolis interactions. The signs of the dipole moment derivatives (∂p/∂Qi) have completely been determined by the least-squares method, and the results were compared with those obtained by the molecular orbital calculation (CNDO/2) and by the analyses of the Coriolis interactions. The local intensity parameters of the CH2 group of this molecule were calculated and compared with the corresponding ones of ethylene.