Deformation-potential theory for the mobility of excess electrons in liquid argon

We investigate the motion of a slow electron in a simple classical fluid in the context of low-field mobility measurements of excess electrons in liquid argon, reported by Jahnke, Meyer, and Rice (JMR). The electron is described in terms of an effective Hamiltonian which is a generalization of the effective-mass Hamiltonian of an electron in a crystal. It is proposed that the primary source of electron scattering is a deformation potential produced by long-wavelength fluctuations of the fluid density. A semiphenomenological theory of the mobility is constructed on this basis. The dependence of the leading deformation-potential coefficient on the fluid density is obtained by fitting the data of JMR to the theory. A calculation of this coefficient based on a previous analysis by Jahnke, Holzworth, and Rice agrees well with that emerging from the data fitting.