Temperature dependencies in dissociative electron attachment to CCl3Br

The study of dissociative electron attachment (DEA) to CCl3Br molecule has been performed in the electron energy range from 0 to about 2 eV and in the gas temperature range from 293K to 478 K using a crossed electron-molecular beams apparatus with a temperature regulated, effusive molecular beam source. Strong enhancement of the negative ion production with the gas temperature has been observed for the overall negative ion yield and for Cl-/CCl3 Br reaction channel at low electron energies (approximate to 0 eV). Activation energies for dissociative electron attachment of (123 +/- 20) meV and (65 +/- 20) meV have been estimated for the overall negative ion formation and for the C l reaction channel. The DEA cross section for Br-/CCl3Br reaction channel was at low electron energies temperature independent. At the 0.6 eV (Br-/CCl3Br) and 0.65 eV (Cl-/CCl3Br) resonances the cross-sections were temperature independent. At the elevated gas temperatures above 422 K, strong decrease of the negative ion yield has been observed for DEA CCl3Br assigned to the catalytic thermal decomposition of molecules on the iron surface of the molecular beam source.