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Slow Debye-type peak observed in the dielectric response of polyalcohols

Rikard Bergman (Institutionen för teknisk fysik, Kondenserade materiens fysik) ; Helén Jansson (Institutionen för teknisk fysik, Kondenserade materiens fysik) ; Jan Swenson (Institutionen för teknisk fysik, Kondenserade materiens fysik)
Journal of Chemical Physics (0021-9606). Vol. 132 (2010), 4,
[Artikel, refereegranskad vetenskaplig]

Dielectric relaxation spectroscopy of glass forming liquids normally exhibits a relaxation scenario that seems to be surprisingly general. However, the relaxation dynamics is more complicated for hydrogen bonded liquids. For instance, the dielectric response of monoalcohols is dominated by a mysterious Debye-like process at lower frequencies than the structural alpha-relaxation that is normally dominating the spectra of glass formers. For polyalcohols this process has been thought to be absent or possibly obscured by a strong contribution from conductivity and polarization effects at low frequencies. We here show that the Debye-like process, although much less prominent, is also present in the response of polyalcohols. It can be observed in the derivative of the real part of the susceptibility or directly in the imaginary part if the conductivity contribution is reduced by covering the upper electrode with a thin Teflon layer. We report on results from broadband dielectric spectroscopy studies of several polyalcohols: glycerol, xylitol, and sorbitol. The findings are discussed in relation to other experimental observations of ultraslow (i.e., slower than the viscosity related alpha-relaxation) dynamics in glass formers.

Nyckelord: dielectric polarisation, dielectric relaxation, liquids, optical, susceptibility, organic compounds, glass-forming liquids, monohydroxy alcohols, room-temperature, relaxation, behavior, 1-propanol, clusters, dynamics

Denna post skapades 2010-02-24. Senast ändrad 2015-03-06.
CPL Pubid: 114382


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Institutionen för teknisk fysik, Kondenserade materiens fysik (1900-2015)



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