Deformation frequencies in the Raman spectra of linear molecules: Acetylene

Summary

Two new bands at Δv 589 and 646 have been recorded in the Raman spectrum of acetylene gas by giving a long exposure. These are interpreted as the maxima of the unresolved O, P, R and S branches of the total symmetric deformation vibration of the acetylene molecule. The negligible intensity of the Q branch and the observed separation of about 57 wave numbers between the bands are in accordance with such an interpretation. The frequency shift of about 615 corresponding to the mean position of the bands is in good agreement with the value deduced from the infra-red absorption for the frequency of this oscillation.