Vibrational Raman spectra of liquid and solid ethylene

The Raman spectra of liquid and solid C2H4 have been examined at a reciprocal linear dispersion of 8 cm−1/mm. The liquid spectrum presents some evidence of short-range order in the liquid near the freezing point. The gerade fundamentals and low-frequency librational modes have been observed in the Raman spectrum of the solid. Analysis of the observed splitting in terms of H-atom repulsion indicates that the intermolecular force constant is 950 dyn/cm, and the crystal structure is P21/n1. The origin of other observed structures is uncertain.