Differential cross sections for collisions of negative halogen ions and alkali atoms

The authors present the relative differential cross sections for collisions of several negative halogen ions with Na and K. The measurements have been carried out in two separate experiments with energy ranges of 5-150 eV and 500-1000 eV and angular ranges of 0-350 and 0-0.30, respectively. It is shown that in both of these experiments elastic scattering is the dominant process. No significant inelastic contribution to the differential cross section, especially no electron detachment, has been observed. The measured differential cross sections are used to obtain information on the anion intermolecular potentials. Comparison of these potentials with the potentials of the neutral molecules shows that all systems investigated have a positive electron affinity over a wide range of internuclear distances. An approximately linear relationship between the dipole moments and the electron affinities is obtained for the halides of the specific alkalis. (Auth.)