Kinetic Theory of Dense Fluids. XII. Electronic and Ionic Motion in Liquid He4I and Liquid He3

Abstract

The mobilities of positive and negative charge carriers in liquid He3 and He4I are calculated and the resultant agreement with experiment is excellent. The negative carrier is taken to be an electron. Due to electrostriction and density fluctuations the effective mass of the electron is of the order of 100 electron masses. In addition, the disorder of the liquid leads to incoherences in the scattering of the electron from atomic pseudopotentials. The positive carrier is taken to be He2+. An extension of the theory of Rice and Allnatt, using the ideas introduced by Mazo and Kirkwood, leads to a formula for the mobility in terms of a quantum-mechanical temperature. Electrostriction increases the density about an ion and the dissipation arises about equally from the short-range repulsive forces and the Coulomb and van der Waals attractive forces. Both calculations involve only basic considerations and there are no adjustable parameters in the theory. The computed effective mass of the negative carrier in He3 at 3.00°K and 2-atm pressure is 105 electron masses: The observed effective mass is 97 electron masses. For the negative carrier in He4I at 4.2°K and 1-atm pressure the computed and observed effective masses are 149 and 128 electron masses, respectively. In the case of the positive ion, the observed mobility at 2.2°K and 1-atm pressure in He4 is 5.6×10—2 cm2 V—1 sec—1 while the computed value is 5.2×10—2 cm2 V—1 sec—1. The reader is referred to the Note added in proof for new comments and alternative interpretation of the electron effective mass.