Dielectric Relaxation of Aqueous Solution with Low-molecular-weight Nonelectrolytes and Its Relationship with Solution Structure.

Dielectric relaxation of water molecules was measured in the frequency range from 0.2 to 20 GHz for aqueous solutions of urea, formamide, alcohols, and saccharides. The relaxation behavior was described well by the Debye equation with a single relaxation process in most cases. The static permittivity of solution and relaxation time of water in solution changed linearly with solute concentration. The relaxation time shift of water molecules through the existence of solute was correlated well to the first virial coefficient of the activity coefficient of water suggesting the close relationship between dielectric relaxation time and aqueous solution structure.