Differential measurements on ion-atom collisions in the energy range 500 eV-3000 eV. III. Ne+on Ne, Ar+on Ar and Kr+on Kr collisions

For Pt. II see ibid., 3, 207 (1970). Elastic and inelastic differential cross sections have been measured in relative values for the symmetrical ion-atom collisions: Ne + on Ne, Ar + on Ar and Kr + on Kr, in the energy range 500 eV-3000 eV and in the angular range 0.5 degrees -13 degrees (lab.). Three types of processes have been observed: elastic, excitation on discrete levels and excitation of the atom on autoionizing levels. The elastic differential cross section shows a double oscillation due to the interference of the Sigma or Pi states of the system. This feature is studied in detail in the case of the Ne + -Ne system for which the calculated cross section is compared to the experimental one. Rather good agreement is found between them, except for the violent collisions, for which a strong absorption appears in the elastic channel. In the case of the Ar + -Ar collision this absorption gives diffraction effects. The excitation processes are dominated by the crossings of the non- adiabatic potential curves. The locations of these crossings have been determined for the Ne + -Ne and Ar + -Ar collisions.