The effects of collision energy and vibrational excitation on H+2, HD++He reactions

Abstract

An experimental study of proton and deuteron transfer in H+2 + He and HD+ + He has been carried out as a function of kinetic and vibrational energy. The data gives evidence that at lower kinetic energies, the spectator stripping mechanism indeed plays an important role when H+2 or HD+ is vibrationally excited. The H+2 (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. Investigation of the competition between both the proton and deuteron transfer channels for the HD+ case, shows that vibrational enhancement towards forming the HeD+ product falls off sooner with increasing kinetic energy than does the HeH+ product again in accordance with the spectator stripping model. The higher yield for HeH+ production at both higher vibrational levels of HD+ and at lower kinetic energy and the behavior of translational energy dependence of HeH+ seems to indicate the importance of the induced orientation of HD+ during the collision with He. Because of the displacement of the center of mass from the center of charge in HD+, the charge induced dipole interaction between He and HD+ tends to swing the H atom more towards He during the approach of He and HD+.