Electron-impact dissociation of XH²⁺ (X=B, C, N, O, F): Absolute cross sections for production of XH⁺ and X⁺ fragment ions

Absolute cross sections for electron-impact dissociation of XH²⁺ (X= B, C, N, O, F) producing XH⁺ and X⁺ ion fragments were measured in the 3- to 100-eV range using a crossed-electron-ion beams technique. Dissociative excitation of BD2+ and CH2+ producing B⁺ and C⁺, respectively, show a propensity toward a two-body dissociation while the remaining species all tend to show a three-body dissociation dynamic. The BD⁺ and CH⁺ dissociative excitation channels show a large resonant-type contribution to the cross sections at 10 eV. For the X ⁺ fragment ion production cross sections, a clear dependence on the threshold energy, as it relates to the rate of rise in the cross section above threshold, is observed.