Infra-Red and Raman Spectra of Polyatomic Molecules. VII. C2D6

The infra-red spectrum of gaseous C2D6 has been investigated from 2 to 22μ, and the Raman spectrum of the liquid has been photographed. These data have been analyzed for both the symmetries D3d and D3h. It is concluded that the equilibrium configuration of ethane cannot be reliably determined from the analysis of the data now available on the vibrational spectra of C2H6 and C2D6. However, the ``uncertain frequency'' of C2H6 is determined by application of the product rule if the symmetry is D3d. A modified valence force type potential function containing interaction terms between the two methyl groups is found to fit the fundamental frequencies of the light and heavy ethanes quite well.