Velocity dependence of the cross section for Penning and associative ionization of argon atoms by metastable neon atoms

Relative cross sections for Penning and associative ionization in Ne*(3P2,0)–Ar collisions have been measured, in a crossed beam experiment, as a function of the collision velocity, in the thermal energy range. The total ionization cross sections have been analyzed, together with other experimental results, obtaining a best fit resonance width function. The analysis of the associative to Penning ionization cross section ratios shows that, in the high collision energy range, the ionization occurs predominantly through the 2Σ1/2 ground state of NeAr+ ion. Some considerations on the role played by the interaction anisotropy in these ionization processes are reported.