Ionization processes in ground-state alkali-noble gas collisions. II. K-Ar

Abstract

For pt.I see ibid., vol.24, no.2, p.439-58 (1991). The authors present the results of an experimental investigation of ionization processes in collisions between fast potassium atoms and thermal argon atoms. The experiments were performed in a crossed-beam apparatus at laboratory collision energies of 100-400 eV. Energy loss spectra of scattered ions at selected scattering angles as well as differential cross sections for some specific ionization channels have been measured. Observed structures in the energy loss spectra are ascribed to K+ ions and recoiled Ar+ ions. In some cases the analysis is complicated due to overlap of projectile and target structures in the spectra. The Ar+ structures are attributed to ion-pair formation of the type K-(3p6nln'l')+Ar+(3p5) and to autoionization of doubly excited Ar**(3p4nln'l') states. Molecular autoionization or Penning ionization in the exit channel might also play a role. Formation of excited ion-pair states like K-(3p6nln'l')+Ar+*(3p4nl) appeared to be unimportant, in contrast with the results of a previous study of similar processes in Na-Ne.