On the Nature of the Debye-Process in Monohydroxy Alcohols: 5-Methyl-2-Hexanol Investigated by Depolarized Light Scattering and Dielectric Spectroscopy

Abstract

The slow Debye-like relaxation in the dielectric spectra of monohydroxy alcohols is a matter of long standing debate. In the present work, we probe reorientational dynamics of 5-methyl-2-hexanol with dielectric spectroscopy and depolarized light scattering (DDLS) in the supercooled regime. While in a previous study of a primary alcohol no indication of the Debye peak in the DDLS spectra was found, we now for the first time report clear evidence of a Debye contribution in a monoalcohol in DDLS. A quantitative comparison between the dielectric and DDLS manifestation of the Debye peak reveals that while the dielectric Debye process represents fluctuations in the end-to-end vector dipole moment of the transient chains, its occurrence in DDLS shows a more local signature and is related to residual correlations which occur due to a slight anisotropy of the $\alpha$-relaxation caused by the chain formation.

arXiv comment5 pages, 5 figures; accepted in Phys. Rev. Lett

References in corpus (5)

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• Susceptibility functions for slow relaxation processes in supercooled liquids and the search for universal relaxation patterns
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• Molecular mechanism of the Debye relaxation in monohydroxy alcohols revealed from rheo-dielectric spectroscopy
• On the Spectral Shape of the Structural Relaxation in Deeply Supercooled Liquids
• Local dielectric response in 1-propanol: $\alpha$-relaxation versus relaxation of mesoscale structures
• Insights into the Non-exponential Behaviour of the Dielectric Debye-like Relaxation in Monoalcohols
• Non-rotational mechanism of polarization in alcohols
• Molecular motion at the experimental glass transition
• Linear-limit aging times of three monoalcohols
• Computing dielectric spectra in molecular dynamics simulations: using a cavity to disentangle self and cross correlations
• Competing Supramolecular Structures: Dielectric and Rheological Spectroscopy on Glycerol/Propanol Mixtures