DISSOCIATION OF POLYATOMIC IONS AT SURFACES - THE INFLUENCE OF MECHANICAL AND ELECTRONIC-ENERGY TRANSFER

The dissociative scattering of CF3+ ions from a clean Ag(111) surface was explored in the energy range 100-600 eV. Both negative (CF3-, CF2- , and F-) and positive ions (CF+ and C+) were formed,The complete diss ociation of the CF3+ molecular ions into C+ fragments was found to be feasible at low (normal) incoming energies. We conclude that the break ing of three C-F bonds is due to concerted electronic and mechanical e nergy transfer. The azimuthal orientation of the crystal has a large i nfluence on the degree of dissociation, which indicates the importance of direct momentum transfer.