Mechanism of thermal energy charge transfer reactions: rare gas ions reacting with NH3 and PH3

Absolute rate constants and approximate product distributions are presented for the reactions of He⁺, Ne⁺, Ar⁺, Kr⁺, Xe⁺, CO⁺ and CO⁺₂ with NH₃ and PH₃. In all cases, electron transfer is the dominant reaction channel. Hydrogen atom transfer is observed in several systems, but only as a minor product, even when this channel is very exothermic. The magnitude of the absolute rate constants can be correlated with the Franck-Condon factors associated with the reactions in most cases. Several exceptions to this general rule are observed that could not be readily predicted a priori. It is speculated that these reactions proceed via a collision complex.