High-freqency dielectric response of hydrogen-bonded liquids between 0.2 and 2.5 thz

Abstract

Using terahertz (THz) time-domain spectroscopy, we measured the complex permittivity of monohydric alcohols and diols in the frequency range of 0.2-2.5 THz at temperatures from 253 to 323 K. The complex permittivities of both monohydric alcohols and diols contain the following three components: (i) a high-frequency tail of dielectric relaxation processes, (ii) a broad vibration mode around 0.5-2.0 THz, and (iii) a low-frequency side of an intermolecular stretching mode located above 2.5 THz. At low temperatures, the dielectric relaxation processes substantially shifted to a low-frequency range. On the other hand, the broad vibration mode around 0.5-2.0 THz was independent of temperature and showed a clear peak in the dielectric loss spectra. Based on the experimental results, it is considered that the broad vibration mode originates from the vibration dynamics of the OH group. The spectral shape and intensity of the broad vibration mode were strongly influenced by both the number and position of the OH groups and the structure of the carbon chain. © 2013 Springer Science+Business Media Dordrecht.