Low-energy electron attachment to brominated methanes

Abstract

The rate constants as a function of the mean electron energy from thermal to about 2 eV at room temperature have been measured for electron attachment to CBr4, CHBr3, CFBr3, CF2Br2, CH2BrCl, CHBr2Cl, and CBrCl3 using the pulse-radiolysis microwave-cavity method combined with microwave heating. The electron attachment cross sections, derived from the rate constant data, all show maximum at zero energy with no noticeable peak at higher electron energies. Based on the differences observed in the absolute magnitude of the cross sections among the brominated compounds as well as those between brominated and the corresponding chlorinated methanes, a model for the dissociative attachment to brominated methanes has been presented.