Dielectric anisotropy of N-methylacetamide in the far-infrared and millimeter-wave region

Far-infrared and millimeter-wave spectra of polycrystalline and single crystal N-methylacetamide (NMA) samples are presented. The far-infrared measurements taken at approximately liquid helium temperature using polarized light reveal several line splittings and anisotropy effects. Anisotropic dielectric properties are also found in the millimeter-wave region. The effect of relaxation processes in double-well potentials on the anisotropic dielectric tensor is calculated. Thereby an estimation of the dipole moment change between the two wells of the high-temperature phase relaxation in NMA can be given.