SIFDT study of the SO+2/H2 H-atom abstraction reaction

The exothermic H-atom abstraction reaction of SO2+ with H-2 has been studied in a selected ion flow drift tube (SIFDT) over a range of center-of-mass energies from thermal (300 K) to about 0.12 eV. The measured rate coefficient at 300 K is 4.2 x 10(-12) cm(3) s(-1) which is very much less than the Langevin capture rate. The increase in rate coefficient with ion kinetic energy gives a linear Arrhenius-type plot with a slope that indicates a barrier of similar to 5 kJ mol(-1) exists on the potential surface. The H2SO2+ potential surface is also explored in an ab initio investigation using the G2 procedure. An (SO2+.H-2)* transition state between reactants and products is identified, corresponding to the barrier found from experiments. (C) 1998 Elsevier Science B.V.