Dielectric relaxation and underlying dynamics of acetonitrile and 1-ethyl-3-methylimidazolium triflate mixtures using THz transmission spectroscopy

The complex permittivity of acetonitrile, 1-ethyl-3-methylimidazolium trifluoromethanesulfonate and mixtures of the two liquids were measured using THz transmission spectroscopy. A number of Debye relaxations to each sample were assigned. Femtosecond terahertz (THz) time domain transmission spectroscopy was used to determine the complex dielectric functions of pure acetonitrile, pure molten salt and their mixtures in the frequency range from 5-50 cm^-1. It was found that the mixtures behaved like electrolyte solutions of a crystalline salt dissolved in a solvent at low molten salt concentrations.