Near thermal charge transfer between Ar+2 and N2

Abstract

The near thermal charge transfer reaction of Ar⁺² with N₂ has been studied at total pressures below 10⁻⁷ Torr using a stored ion technique. Ar⁺² ions produced by electron impact double ionization of Ar gas were selectively stored for times the order of seconds in a split‐ring Penning‐type ion trap. The decay with time of the initial ion sample number in a mixture of Ar and N₂ gases was fit to the sum of two exponentials, corresponding to different reaction rates for the ³P and ¹D low‐lying Ar⁺² levels. The observed Ar⁺² number decrease is attributed to the double‐charge transfer process Ar⁺²+N₂→Ar+N₂⁺²→Ar+N⁺+N⁺ in accord with recent flow‐tube measurements. A rate constant for the metastable Ar⁺² (¹D) level reaction with a value k(¹D)=1.4×10⁻⁹ cm³/sec is obtained, using the previously measured rate constant for the Ar⁺²(³P) state.