ELASTIC SCATTERING OF POTASSIUM IONS IN ENERGY RANGE 150-4000-EV WITH ARGON

The incomplete integral cross section of the elastic scattering of K+ ions versus Ar atoms was determined in the energy range from 150 through 4000 eV by passing a well defined beam of K+ through a collision chamber filled with Ar gas at room temperature. The pressure of the gas was about 7 × 10-3 torr. The results can be represented by the inverse power potential ( K rs), however, with K and s functions of the internuclear separation. The exponential potential (A exp - αr) gives a good representation over almost the whole energy range with a single set of parameters: A = 4400 eV, α = -3.95 Å-1. The cross section was compared with that of the isoelectronic system of fast Ar-atoms in the same energy range colliding with thermal Ar-atoms. A reduction of 10% was found in the diameter of the electron cloud in going from Ar to K+. At the energies of 1000, 2000 and 4000 eV the cross section for 41K+ was measured and it was found to be equal to the values for 39K+ within experimental error. © 1969.