Experimental investigation of the He+ - CO2 charge exchange collision

The dissociative charge exchange collision between He+ and CO2 has been investigated by means of a crossed-beam scattering experiment. Relative cross sections differential with respect to energy and angle were measured for the fragments O+, CO+, and C+, for He+ in the range 8.7 eV to 200 eV. For He+ kinetic energies above about 20 eV, it has been found that the charge exchange is near-resonant. It is possible to identify the state of CO2+ produced (a 2II/sub u/, or a 2Phi/sub u/) and to predict the branching ratios for the ionic fragments by use of the quasiequilibrium theory of mass spectra. For He+ energies below about 20 eV, it has been found that the collision proceeds via a long-lived complex. Complex formation is usually not observed at this high an energy. A model for this process coupling dissociation with inelastic energy transfer is proposed