Electron ionization of cyclohexene

The absolute total cross section of electron ionization on cyclohexene (CHE) and the branching ratios of the product ions are measured in an electron energy range of 10-200 eV. The total cross section reaches a maximum of 1.5 × 10−15 cm2 at 80 eV. Sixteen noteworthy product ions are observed from the ionization of CHE that have partial cross sections greater than 5 × 10−18 cm2 at 50 eV: C2H3+, C3H3,5+, C4H2-7+, C5H5-7+, and C6H5,7,9,10+, where branching ratios are reported for each. The most abundant ions within the electron energy range studied are the parent ion C6H10+ and fragment ions C5H7+ and C4H6+, with combined abundance accounting more than half of the ion population. The reaction pathways forming certain fragment ions at energies near their thresholds are discussed.