Relation between Dielectric and Low-Frequency Raman Spectra of Hydrogen-Bond Liquids

Abstract

We analyzed the complex dielec. and Raman spectra of hydrogen-bond liqs. in the microwave to terahertz frequency range. As for water and methanol, the high-frequency component of the dielec. spectrum, i.e., the small deviation from the principal Debye relaxation, clearly corresponds to the Raman spectrum. This indicates that the cooperative relaxation, accompanied by huge polarization fluctuation, is virtually not Raman active, whereas the faster processes reflect common microscopic dynamics. For ethylene glycol, the shape of the Raman spectrum also resembles that of the high-frequency deviation of the dielec. spectrum, but, addnl., a weak manifestation of the cooperative relaxation arising from quadrupolar conformers is detected.