Electron-exposure effects on desorption of F- (Cl-) and F+ (Cl+) ions fromadsorbed CF2Cl2

Electron-exposure effects on the desorption of F- (Cl-) and F+ (Cl+) ions f rom 1 ML CF2Cl2/ Ru(0001), 1 ML CF2Cl2/1 ML Xe/Ru(0001) and 5 hit CF2Cl2/Ru (0001) surfaces have been studied. It is observed that for a less than or e qual to 1 ML CF2Cl2/Ru surface, the anion yield shows a rapid decrease with increasing electron exposure, while the cation yield exhibits an increase. In contrast, an opposite behavior is observed for a 5 ML CF2Cl2/Ru surface . For 1 ML CF2C12 adsorbed on a 1 ML Xe-spacer layer, the effect tends to s witch the behavior from the monolayer to the multilayer. These results indi cate that Cl- ions accumulated on the multilayer or the monolayer surface o n a Xe spacer by the polarization potential have an electrostatic effect on the desorption yields of anions and cations. Moreover, from the attenuatio n of the F- yield of a 1 ML CF2Cl2-covered surface with electron exposure, the electron-induced dissociation is estimated to be 9.2(+/-2.0) x 10(16) c m(2).