MEDIUM ENHANCED, ELECTRON-STIMULATED DESORPTION OF CF3- FROM CONDENSED CF3I

It is shown that (a) the cross-section for electron stimulated desorpt ion of CF3- from condensed CF3I is enhanced by more than 2 orders of m agnitude with respect to the corresponding gas-phase dissociative elec tron attachment cross-section and (b) CF3- is ejected from the CF3I fi lm into vacuum with surprisingly high kinetic energy. These observatio ns are explained by a preferential orientation of the molecule at the surface and a particular, medium enhanced, desorption mechanism which is based on the conversion of an open-channel resonance into a closed- channel (Feshbach) resonance when solvated. (C) 1998 Elsevier Science B.V. All rights reserved.