Abstract
The basic framework for understanding the quasi-free electron mobility and the probability of free-carrier generation following an ionization event in a high-mobility liquid is critically reviewed from the point of view of application to liquid ionization chambers. The relationship between these two physical quantities is empirically well-established. Theoretically the Sano-Mozumder model provides a fair description for hydrocarbon liquids. The corresponding situation for liquefied rare gases is somewhat uncertain. However, it is clear that a successful theory for these liquids must consider impurity effects and an effect attributable to the field dependence of mobility.