Elastic Electron Scattering in Potassium

Abstract

A method was developed for the measurement of slow electron scattering in vapors. Angular distribution curves from 25° to 160° were obtained for 5, 10, 15, 25, 50, 75, 100 and 150 volt electrons elastically scattered by potassium atoms. All curves contained a large peak near 100°. The scattering curves fell off rapidly for angles up to about 60° and rose rapidly for angles greater than about 130°. The position of the peak was found to shift to larger and then smaller angles as the energy of the colliding electrons was decreased. Henneberg's calculations which employ the Thomas-Fermi atomic field were found to give scattering curves whose general shapes agree quite well with the experimental curves. Best agreement occurred for the 5 and 50 volt electrons. When the potassium and argon experimental curves were compared it was found that the curves were quite similar for electron energies of 50 volts or more. For slower electrons the curves became more dissimilar.