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 similar to4 eV and a peak in the Cl- yield at similar to7 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 Cl-2 in the condensed phase induced by electron irradiation of the CF2Cl2 film. This Cl-2, formation is demonstrated by the observation in the Cl- yield of the Cl-2(-)/Cl-2 (2)Pi (u) resonance state, and by Cl- kinetic energy distributions that are similar to those obtained from condensed pure Cl-2 films. (C) 2001 American Institute of Physics.