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Various relaxation procedure in the supercooled state of D-xylose have been investigated using dielectric spectroscopy over a wide frequency (1 mHz – 10 MHz) and temperature range (140-350 K). The main relaxation process (α) that is accountable for the glass transition phenomena, another secondary relaxation process is also visible below glass transition temperature. The attached hydroxymethyl (-CH2OH) side group to the sugar ring might be responsible for this process. In addition, we have applied Coupling model to find the location of intermolecular relaxation below the glass transition temperature (Tg). The dependence of various dielectric parameters viz. τα, τβ, τγ and τβ cm on temperature have been critically examined. The current experimental result shows that, log10 σdc vs. log10 τα dependence is nonlinear and hence can be described with the fractional Stokes-Einstein-Debye relation.

High frequency dielectric spectroscopy has been used to investigate the dielectric behavior of the pure as well as the aqueous solutions of 2-ethyl-1-hexanol at 270 and 300 K. It was found that the strength of Debye peak decreases systematically with increasing concentration of water. This behavior has been explained on the basis of the fact that alcohol favors more reduced structure in presence of water. This result is consistent with the simulation work as well as low frequency dielectric results on alcohol-water system.

It is well established that many mono-hydroxy alcohols show an extra relaxation process of the Debye type in addition to the signatures of primary and secondary structural relaxations, which is observed only in dielectric spectroscopy and related techniques. In order to gain further insight into the nature of this Debye peak, we study the linear and nonlinear dielectric behavior of a series of isomeric octyl alcohols and of mixtures of n-propanol with one of the octanols. These samples display systematic variations of the Debye peak intensity and concomitant changes in the Kirkwood correlation factor gK from 0.1 to 4, indicative of different equilibrium constants, K(c∕r), that characterize the populations of non-polar ring and polar open chain structures. For cases where K(c∕r) is not too far from unity, we find that a high electric field shifts K(c∕r) towards more chains, and that the accompanying change in the end-to-end vector of hydrogen-bond connected structures occurs on the Debye time scale. The results suggest that gK is correlated with the spectral separation of the Debye and primary structural peaks, as both features depend on steric hindrance of chain flexibility or bond rotation barriers and on average chain lengths. Based on the complex dynamics of supercooled mono-hydroxy alcohols with three relaxation peaks that cover many orders of magnitude in frequency, it is argued that a frequency dependent gK may be required for assessing the average orientational correlations within hydrogen-bonded structures correctly.

In hydrogen-bonded liquids including monohydroxy alcohols, the prominent Debye process that often dominates the dielectric relaxation behavior is associated with hydrogen bonding, but its microscopic origin has remained unclear to date. High electric field impedance spectroscopy on 5-methyl-3-heptanol reveals a field-induced change in the Kirkwood-Fr\"ohlich correlation factor ${g}_{K}$, viewed as evidence for an electric field driven conversion from ring- to chain-type hydrogen-bonded structures. The concomitant rearrangement of the chain structure is observed to occur on the time scale of the Debye process, suggesting that the Debye peak of monohydroxy alcohols originates from a fluctuation of the net dipole moment via ${g}_{K}$ of the chain structures on a time scale that is largely controlled by viscosity.

A two-channel impedance technique has been used to study the relaxation behavior of 2-ethyl-1-hexanol with polar and non-polar dopants at the few percent concentration level over a wide temperature and frequency range. The non-polar dopants shift both the Debye and the primary structural relaxation time in the same direction, to shorter times for 3-methylpentane and to longer times for squalane, consistent with the relative glass transition temperatures (Tg) of the components. By contrast, polar dopants such as water or methanol modify the α-process towards slower dynamics and increased amplitude, while the Debye process is accelerated and with a decreased amplitude. This effect of adding water to alcohol is explained by water promoting more compact structures with reduced Kirkwood correlation factors. This picture is consistent with a shift in the neutron scattering pre-peak to lower scattering vectors and with simulation work on alcohol-water systems.