Thermal-electron scattering by polar molecules

Abstract

The temperature dependence of the drift velocity of thermal electrons travelling through polar gases has been investigated, and the data have been used to determine more accurately the magnitude and the velocity dependence of the momentum transfer cross section sigma _m, expressed as sigma _m=a_alpha / nu ^alpha , where A_alpha is a constant for each value of alpha . The values of alpha for the 14 polar molecules investigated are found to be close to the value of 2 predicted by the Born approximation. There is a considerable spreading in sigma _m for permanent electric dipole moments mu in the region 1.65<or= mu <or=3 debye.