Temperature dependence of dissociative electron attachment to 1-bromo-2-chlorobenzene and 1-bromo-3-chlorobenzene

Abstract

Dissociative electron attachment (DEA) to 1-bromo-2-chlorobenzene (1,2-C 6H 4BrCl) and 1-bromo-3-chlorobenzene (1,3-C 6H 4BrCl) is studied in a crossed electron/ molecular beams experiment in the electron energy range between about 0 and 2 eV and in the gas temperature range from 377 to 583 K. For both molecules the two fragment anions Cl − and Br − are formed. The ion yields of both Br − and Cl − show a pronounced temperature effect when the gas temperature is raised from 377 to 583 K. These DEA processes can be well interpreted qualitatively with thermodynamics calculations within adiabatic approximation scheme, in particular, the thermally excited out-of-plane bending and C–Cl/Br bond stretching vibrations may be closely related to the Cl −/Br − branching of the temporary negative anions of 1,2- and 1,3-C 6H 4BrCl.