Electron mobility in dense gases of deuterated methanes as functions of electric field strength, temperature, and density

Abstract

Values of electron mobility μ were measured in gaseous deuterated methanes CHxD4−x(x=0–4) as a function of density normalized electric field strength at 0.2≤n/1026 molecule m−3≤61=nc (subscript c denotes critical fluid), and 98≤T/K≤433. The mobility at low E/n had a constant value μ0 but at fields above a threshold (E/n)th, μ increased. In the saturated vapor the ratio of the electron drift velocity at (E/n)th to the speed of sound in the vapor was determined mainly by T, while nμ0 was mainly determined by n; there was no clear isotope effect. The effect of density on nμ0 is discussed in terms of the deformation potential and dielectric screening models. The former fits better.