Populations of Ethanol Conformers in Liquid CCI4 and CS2 by Raman Spectra in OH Stretching Region

Combining Raman spectroscopy with density functional theory, the populations of the trans- and gaucheethanol conformers are investigated in carbon tetrachloride （CC14） and carbon disulfide （CS2）. The spectral contributions of two ethanol conformers are identified in OH stretching region. The energy difference between both conformers is estimated with the aid of the calculated Raman cross sections. It can be seen that the trans- ethanol is more stable in CC14 and CS2 solutions. The spectra are also obtained at different temperatures, and it is found the van＇t Hoff analysis is invalid in these solutions. By taking accounts of the Boltzmann distribution and theoretical Raman cross section, the energy difference is found to be increased with temperature, which shows the weak intermolecular interactions can enhance the population of transethanol.