KINETIC-ENERGY RELEASE OF F- DESORPTION FROM CONDENSED CF4 FOLLOWING LOW-ENERGY-ELECTRON IMPACT

The kinetic energy release of desorbed F-ions formed via dissociative electron attachment (DA) to condensed CF4 is measured by means of an e lectrostatic energy analyzer. The condensed phase results are compared to DA from gas phase CF4 where F- appears with high kinetic energy fr om a feature at 6.2 eV (assigned as CF4- (T-2(2)) Shape resonance) and with low kinetic energy from a second feature located at 7.7 eV (assi gned as a Feshbach type CF4- resonance with TI symmetry). in contrast , the kinetic energy of desorbed F-continuously increases with electro n energy over the entire range of the resonance feature (5-9 eV) with a slope of 0.25 for the most probable energy of F-. The present result s indicate that the transfer of electronic energy into nuclear motion is considerably modified in the condensed phase. (C) 1997 Elsevier Sci ence B.V.