Effect of collision energy and vibrational excitation on endothermic ion-molecule reactions

This thesis is divided into two major parts. In the first part an experimental study of proton and deuteron transfer in H2+ + He and HD+ + He was carried out as a function of kinetic and vibrational energy. The data give evidence that at lower kinetic energies, the spectator stripping mechanism indeed plays an important role when H2+ or HD+ is vibrationally excited. The H2+ (v = 0) reaction has a much smaller cross section than the v = 1-4 reactions and seems to go through intimate, small impact parameter collisions involving all the atoms. The second half of this thesis examines the relative efficiencies between the excitation of C-C stretching vibration and collision energy on the promotion of the H atom transfer reaction of C2H2+ + H2 → C2H3+ + H. At low collision energies, the reaction is strongly vibrationally enhanced in agreement with previous thermal energy studies. Translational energy was found to be not as effective as exciting the C-C stretching vibration in promoting the reaction