DIELECTRIC-RELAXATION SPECTROSCOPY OF ELECTROLYTE-SOLUTIONS - SOME LI-SALTS IN N-METHYLPYRROLIDONE AND N-CYCLOHEXYLPYRROLIDONE

Broadband measurements (about 10 kHz to 70 GHz) of the dielectric func tion (particularly of dielectric loss epsilon''(omega)) are reported f or solutions of LiClO4, LiCl and LiNO3 in N-methyl-2-pyrrolidone and N -cyclohexyl-2-pyrrolidone at 20-degrees-C. The choice of these chemica lly related solvents allows to compare solutions over a large range of viscosities. After subtraction of the conductivity contribution, all spectra can be analyzed into a lower frequency Debye term and a higher frequency Cole-Davidson term, which are discussed as due to ionic spe cies and solvent, respectively. The correlation of relaxation times an d viscosity is such that the confined translational motion of ions is likely to contribute to the low frequency relaxation.