Abstract
We discuss a simple model for the localized hopping of a charged particle in a rearranging structural environment, whose dynamics are described by an overdamped Brownian motion. We find that the dipolar relaxation strongly depends on how the bare jump frequency ν of the particle and the characteristic structural relaxation time τs of its environment relate to each other. For ντs ≪ 1 the imaginary part of the dielectric susceptibility χ″(ω) exhibits a single-peak pattern. while for ντs ≳ 1 a second smaller peak appears at higher frequencies, which becomes more separated from the first peak with increasing ντs. It is suggested that this behaviour provides an explanation for the decoupling phenomenon of secondary β relaxations from the main primary α relaxations as is often observed close to a glass transition.