Penning ionization of a van der Waals molecule: He*(2 1S, 2 3S)+Ar2→He+Ar+2 +e

Abstract
The collision energy dependence of the cross sections for Penning ionization in the title systems has been measured in a crossed beam experiment in the range 1.5–6.0 kcal/mol. Comparison with the corresponding monomer ionization and with theory based on a sudden approximation indicates unusual behavior in the 3S system.