Raman and far-infrared spectra of crystalline formaldehyde, H2CO and D2CO

Raman and far‐infrared spectra of crystalline formaldehyde and its fully deuterated analogue have been recorded over the frequency range 25–350 cm−1 and at temperatures of 80 and 20 K; 16 Raman and 8 far‐infrared lattice peaks have been resolved. Isotopic frequency shifts together with inertia and intensity arguments are used to assign the peaks. Raman spectra of the internal vibrational modes of solid formaldehyde are also presented, with several crystal field splittings observed. The results are consistent with a group theoretical analysis based on the molecular and crystal symmetries.