Dielectric permittivity of aqueous solutions of electrolytes probed by THz time-domain and FTIR spectroscopy – Phys. Lett. A.
A. De Ninno, E. Nikollari, M. Missori and F. Frezza have published Dielectric permittivity of aqueous solutions of electrolytes probed by THz time-domain and FTIR spectroscopy in Physics Letters A.
• The permittivity of water is described in terms of two independent Debye functions.
• The model is also applied to chloride solutions.
• The excess high frequency response is explained without ad hoc corrective terms.
• The model explains why LiCl is more transparent than pure water to THz radiation.
We have measured the dielectric permittivity of pure water and aqueous chlorides solutions in the range 0.2-1.5 THz. We considered the relaxation spectral function as the weighted sum of two independent single-parameter Debye functions. Such an approach allowed to drastically reduce the number of the parameters used in the fit which we set only by physical considerations. The resulting functions allow to fit the experimental data for pure water and solutions of LiCl, KCl, NaCl, and CsCl and to predict the excess response on the high frequency side of the relaxation without “ad hoc” corrective terms.