Low-energy electron-induced processes in condensed CF2Cl2 films

We report measurements of electron stimulated desorption yields and kinetic energy distributions for F− and Cl− anions from thin films of CF2Cl2 condensed on polycrystalline platinum at 20 K. Dissociative electron attachment processes cause a peak in the F− yield at an electron energy of ∼4 eV and a peak in the Cl− yield at ∼7 eV. After electron irradiation, a new dominant structure appears in the Cl− yield at 5 eV incident electron energy, and Cl− ions having high kinetic energy (>1 eV) are observed in the kinetic energy distributions. These changes are attributed to the synthesis of Cl2 in the condensed phase induced by electron irradiation of the CF2Cl2 film. This Cl2 formation is demonstrated by the observation in the Cl− yield of the Cl2−/Cl2 2Πu resonance state, and by Cl− kinetic energy distributions that are similar to those obtained from condensed pure Cl2 films.