lon molecule reactions in vinyl fluoride by photoionization . Effects of vibrational excitation on major reaction pathways *

Photoionization methods have been used to study the reactions of the molecular ion in vinyl fluoride to yield the ionic products C3H 3F{, C3H 4F+, and C3Ht. Quantitative measurements are reported of the effect of the vibrational state of the reactant ion on the product distribution and overall reaction cross section. Reaction cross sections for all three channels decrease with reactant internal energy. The effect on the reaction pathway producing C3H 3F{ is especially pronounced, with 0.18 eV of vibrational excitation being sufficient to reduce the reaction probability by 75%. Deactivation of vibrationally excited reactant ions competes with the reaction and is shown to be an efficient process.