Watching Hydrogen-Bonded Structures in an Alcohol Convert from Rings to Chains

Abstract

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-Fröhlich 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.