ELECTRON-EXPOSURE EFFECTS ON DESORPTION OF F-(Cl-) AND (F+)(Cl+) IONS FROM ADSORBED CF2Cl2

Abstract

Electron-exposure effects on the desorption of F -( Cl -) and F +( Cl +) ions from 1 ML CF 2 Cl 2 /Ru(0001), 1 ML CF 2 Cl 2/1 ML Xe/Ru(0001) and 5 ML CF 2 Cl 2/Ru(0001) surfaces have been studied. It is observed that for a ≤1 ML CF 2 Cl 2/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 CF 2 Cl 2/Ru surface. For 1 ML CF 2 Cl 2 adsorbed on a 1 ML Xe-spacer layer, the effect tends to switch the behavior from the monolayer to the multilayer. These results indicate that Cl - ions accumulated on the multilayer or the monolayer surface on a Xe spacer by the polarization potential have an electrostatic effect on the desorption yields of anions and cations. Moreover, from the attenuation of the F - yield of a 1 ML CF 2 Cl 2-covered surface with electron exposure, the electron-induced dissociation is estimated to be 9.2(± 2.0) × 1016 cm 2.