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.