Chemi-ionization in the metastable neon–metastable argon system

Studies were made by a merging-beams technique of the associative ionization (AI) reaction (1) Ne*+Ar*→NeAr++e and the Penning ionization (PI) reactions (2) Ne*+Ar*→Ne+Ar++e and (3) Ne*+Ar*→Ne++Ar+e. The relative kinetic energy of the reactants was varied from 0.01 to 10 eV. The Ne* and Ar* each represents a composite of the metastable 0P2,0 states. There is a complication in the present investigation which arises because AI and PI occur in collisions of Ne* with ground-state Ar. Since the reactant beams consist of metastable as well as ground-state species, the measurements are composites of chemi-ionization in both the Ne*–Ar* and Ne*–Ar systems. Information on AI and PI for the Ne*–Ar* system is obtained by subtracting from these composite measurements known contributions of the Ne*–Ar system. From such information it appears that the molecular states of the reactants are different for reactions (2) and (3).