Infra-Red and Raman Spectra of Polyatomic Molecules. III. Ethane

The Raman and infra-red spectra of ethane have been re-examined. The 993, 2900, and 2955 cm—1 Raman lines are polarized; there were indications of very faint lines appearing at 620 and 820 cm—1. The strong infra-red peak at 1480 cm—1 is found to be a single minimum; the weak band at 1740 cm—1 is confirmed. The available Raman and infra-red data are evaluated, and possible assignments discussed. It is shown that the observed frequencies do not require a 740 cm—1 fundamental, but are consistent with an ``uncertain frequency'' of about 1100 cm—1 and a high restricting potential.