Physics & Engineering Physics

Juin Zhou, FCRH ’16, Stony Brook University, will present “Effective Debye relaxation models for binary solutions of polar liquids in the terahertz frequencies.”

There are many effective media models that accurately describe the dielectric properties of mixtures. However, these models assume that the components are non-interacting. This assumption is not valid for solutions of polar liquids, resulting in significant deviations between the measured and theoretically predicted complex index of refraction of the mixtures. We present three effective media theories by expanding the well-known Debye relaxation model for solutions of polar liquids in the terahertz (THz) regime. The new effective media models proposed in this paper predict the individual relaxation Debye parameters based on the cooperative motion dynamics and self-associative properties of each mixture, and therefore explain the deviation of the dielectric functions of the solutions from the traditional effective media models. These models are verified through reflection measurements of four alcohol-water solutions acquired through THz time-domain spectroscopy (THz-TDS). Compared to the current mixed media models, the new effective Debye theorem predicts the dielectric properties of polar solutions more accurately, and has the potential to explain inter-species mixing schemes and interactions.