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 conde nsed on polycrystalline platinum at 20 K. Dissociative electron attachment processes cause a peak in the F- yield at an electron energy of similar to4 eV and a peak in the Cl- yield at similar to7 eV. After electron irradiati on, a new dominant structure appears in the Cl- yield at 5 eV incident elec tron energy, and Cl- ions having high kinetic energy (>1 eV) are observed i n the kinetic energy distributions. These changes are attributed to the syn thesis of Cl-2 in the condensed phase induced by electron irradiation of th e CF2Cl2 film. This Cl-2, formation is demonstrated by the observation in t he Cl- yield of the Cl-2(-)/Cl-2 (2)Pi (u) resonance state, and by Cl- kine tic energy distributions that are similar to those obtained from condensed pure Cl-2 films. (C) 2001 American Institute of Physics.