Cross Section Calculations for Electron-Impact Ionization of Pyrimidine Molecule and its Halogenated Derivatives: 2-Chloropyrimidine, 5-Chloropyrimidine, 2-Bromopyrimidine and 5-Bromopyrimidine

Total cross section for single electron-impact ionization of pyrimidine (C4H4N2), 2–chloropyrimidine (2-C4H3ClN2), 5–chloropyrimidine (5-C4H3ClN2), 2–bromopyrimidine (2-C4H3BrN2) and 5–bromopyrimidine (5-C4H3BrN2) molecules has been calculated with the binary-encounter-Bethe model from the ionization threshold up to 5 keV. The input data for the BEB calculations concerning electronic structure of the studied targets have been obtained with quantum chemical methods including the Hartree-Fock (H-F) and the outer valence Green function (OVGF) methods. The calculated cross section for ionization of pyrimidine molecule due to electron impact is compared with available experimental and theoretical data. The question of the magnitude the pyrimidine ionization cross section is also discussed. Efficiency of the ionization process of studied halogenated derivatives of pyrimidine is also discussed.