THz insight into Debye relaxation in liquid water: Link to self-diffusion and viscosity

Abstract

A non-standard analysis of the dielectric loss spectrum of liquid water in the Debye relaxation region (108–1013 Hz) is carried out in terms of dynamic conductivity σ(ν), with the Debye dielectric loss dome represented as the spectral trapezoid of an overdamped Lorentzian oscillator. Debye relaxation, in this framework, reflects the low-frequency tail of a strongly overdamped molecular oscillatory process with a characteristic frequency around 0.3 THz. The effectiveness of the σ-approach for identifying the relationship between the dielectric response and the self-diffusion D and viscosity η coefficients of liquid water is shown. Analytical expressions that link the dielectric and transport parameters of liquid water over a wide temperature range, from the triple point to the critical point (273–647 K), are derived.