Field-dependent electron mobility in methane–ethane liquid mixtures

Abstract

Some aspects of the mobility of excess electrons in liquid hydrocarbons are discussed. Certain salient features of the experimental data on high-field mobility in ethane–methane mixtures are explained in terms of a hopping model, in which disorder plays an important role. The disorder is compositional, like that in a binary alloy, and enters the model in the form of two distinct jump distances for hopping motion. It is shown that decreasing the coherence length for a quasi-free electron increases the binding energy of a localized electron and hence affects the activation energy and rate of hopping. The effects of temperature and impurity concentration for high-mobility liquids are shown to be consistent with a scattering model.