A possible explanation of intermediate frequency absorption/loss in polar liquids through a non-linear itinerant oscillator model

The itinerant oscillator (IO) model offers a useful theoretical explanation of the experimentally observed dielectric loss and power-absorption spectra of polar liquids in terms of motion on the molecular level. Most of the previous work on the IO assumes that the non-linear cosine potential which couples a molecule of the liquid to its surroundings can be approximated by the equivalent harmonic-oscillator potential, i.e. Cos θ≃θ. Such an assumption simplifies the subsequent analysis but ignores the inherent non-linearity of the potential. In this paper two different ways of including non-linearities into the existing framework of the model are described in brief and some theoretical loss spectra are compared with loss spectra of the linear model. The significance of the present work in the context of the findings of Gerschel et al. (1985) is also described