Chemi-ionization in collisions of metastable neon with argon

Absolute and relative cross sections were obtained for the Penning-ionization (PI) reaction Ne*+Ar→Ne+Ar⁺+e and the associative-ionization (AI) reaction Ne*+Ar→NeAr⁺+e by a merging-beams technique over a range of interaction energies W from 0.01 to 600 eV. The Ne* represents a composite of Ne(3s³P₂) and Ne(3s³P₀). The PI cross section Q_Ar⁺ rises with decreasing W except for a small dip near 0.05 eV and exhibits a rather weak dependence on W. For a change of almost five orders of magnitude in W, Q_Ar⁺ only changes by about a factor of 7. The AI cross section Q_NeAr⁺ monotonically increases with decreasing W and shows a large dependence on W. The Q_NeAr⁺ at $W=0.01$ eV is about 70 times larger than that at 0.5 eV. The total cross section QT=Q_Ar⁺+Q_NeAr⁺ is compared with theoretical and other experimental values. At low W our absolute QT are considerably larger than those of Tang, Marcus, and Muschlitz although the relative QT for both experiments are in fair agreement.