Low temperature Raman spectra of NH3SO3 and ND3SO3 single crystals

The Raman spectra of NH3SO3 and ND3SO3 single crystals at 300 and 30 K have been studied in the 4000 to 5 cm−1 range. Infrared spectra of polycrystalline samples have been recorded for comparison in the 4000 to 60 cm−1 region. Twenty‐three Raman and six infrared lattice modes from respectively twenty‐four and fifteen expected ones have been observed. An assignment in terms of factor group symmetry species, rotational and translational vibrations is given. Static and correlation field splitting of internal vibrations is discussed and an assignment of the bands to group frequencies and molecular and factor group symmetry species is proposed. Torsional vibrations are discussed with respect to the amplitude of this motion and the potential barrier opposed to the rotation of the NH3 group has been determined. The NH stretching frequencies are correlated with the N…︁O distances and the v NH band breadth and structure are discussed.