Negative Chemical Ionization Mass Spectrometric Study on the Dissociative Electron Attachment to Halogenated Ethane

Abstract

The temperature dependence for the formation of negative ions from Cl₂BrC-CBrCl₂, FClBrC-CBrF₂, and ClBr₂C-CF₃ was studied using negative chemical ionization mass spectrometry. Halide ions and halogen molecular anions were observed. The intensity ratios between the halide ions and halogen molecular anions were almost equal to F₂BrC-CBrF₂. Halogen molecular anions are produced from halogen atoms presented by each C atom: the four-center elimination. The temperature dependence of the ion intensity ratios, Br^-/Cl^- and Br₂^-/BrCl^-, suggests that the strength of the bonding energy of the C-Cl relative to C-Br increases in the order of Cl₂BrC-CBrCl₂<FClBrC-CBrF₂<ClBr₂C-CF₃.