Temperature- and frequency-dependent dielectric studies of p-fluorophenylacetonitrile–methanol mixtures using time-domain reflectometry

Abstract

Using picosecond time-domain reflectometry, dielectric relaxation studies have been carried out for p-fluorophenylacetonitrile(FPA)–methanol(MeOH) mixtures over the frequency range 10 MHz–10 GHz at various temperatures. The relaxation in these systems can be described by a single relaxation time using the Debye model. The excess dielectric properties, Kirkwood correlation factor and thermodynamic properties of the mixtures have been determined. The Kirkwood correlation factor of pure FPA is 0.4, although FPA is highly polar in nature (µ= 4.85 D), suggesting antiparallel orientation of its electric dipoles. Addition of MeOH to FPA is found to break the antiparallel orientation effectively, leaving behind monomers and causing positive excess permittivity.