Molecular conformers in gas-phase ethanol: A temperature study of vibrational overtones

Overtone absorption spectra are reported for ethanol vapor (10150–19900 cm^?1) measured by intracavity photoacoustic spectroscopy. The OH overtones are composed of two sub-bands which are assigned as the transitions of two conformers of the OH bond in the trans or gauche position with respect to the methyl group. From the temperature dependence of the OH overtone intensity we determine the enthalpy difference between the conformers to be 0.7 ± 0.1 kcal/mole.