Dielectric Relaxation at High Frequencies

A theory of dielectric relaxation is presented which is based on using an interpolation function to represent a classical correlation function which is analytic at the origin and becomes exponential at sufficiently long times. The Fourier transform of this interpolation function is a relatively simple analytical function of frequency which has the Debye character at low frequencies but decreases essentially exponentially in the high-frequency wing. The parameters in the correlation function are discussed in terms of relaxation due to reorientational diffusion. Our model predicts practically the same absorption in the microwave region and somewhat more absorption in the far-infrared region as theories of dielectric relaxation which include the effect of rotational inertia, but in agreement with experiment predicts very much smaller absorption in the infrared region.