Ethanol-OD is a molecule which is well suited for a study of the fine structure of the OX (X = H, D) stretching vibrational profile resulting from rotational isomerism, using Raman spectrometry. The pronounced triplet structure is correctly reproduced by a quantum-mechanical calculation on the basis of interaction between the stretching and torsional motions of the OD group. As a result, the third band between the trans and gauche doublet components can be assigned to stretching vibrational transitions in torsionally excited states with τ≥2. The temperature dependence of the profile observed between 373 and 553 K appears to be a section of a more general evolution from a doublet structure at low temperature to a singlet at high temperature, due to the decrease of the intramolecular interaction with growing torsional excitation. © 1990.
