Measurements of thermal energy neon ion—neutral reaction rate coefficients and product ion distributions

Reaction rate coefficients and product ion distributions have been measured for the reaction of Ne⁺ with H₂, N₂, CO, CO₂, N₂O, CH₄, O₂, NO, NH₃, SO₂, CH₃Cl, COS, H₂O and C₂H₄ at 300 K using a selected ion flow tube (SIFT) apparatus. In most cases the major reaction channel involves dissociative ionization while for N₂, CO⁺, H₂O, CH₄ and CH₃Cl these reactions proceed mainly or exclusively by simple charge transfer. For H₂ the process is exclusively hydrogen atom abstraction. The measured rate coefficients are compared with the values given by the Langevin and average-dipole orientation theories of ion—molecule collisions. In general the reaction probability (ratio of measured rate to the Langevin or ADO rate) is greater for the dissociative ionizaton reactions, although H₂O is an exception with quite fast simple charge transfer.