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Absolute cross sections for electron-impact ionization and dissociation of NO+ ions are reported. Simple ionization to NO2+ ion and production of singly charged N+ and O+ and doubly charged N2+ and O2+ fragments have been investigated. The animated electron-ion crossed-beam method is applied in the energy range from the respective thresholds up to 2.5 keV. The maximum of the simple ionization cross section is found to be (3.49 ± 0.07) × 10−17 cm2 at 135 eV. The total cross sections for N+ and O+ fragments at the maximum are found to be (13.9 ± 1.0) × 10−17 cm2 and (14.0 ± 1.4) × 10−17 cm2, respectively, both at an energy of 85 eV. By performing careful magnetic field scans of the detected signal, contributions of dissociative excitation and dissociative ionization to N+ and O+ production are determined separately. The cross sections for asymmetric dissociative ionization to N2+ and O2+ are found to be over one order of magnitude smaller. Distributions of the kinetic energy release to the fragments are determined for all dissociation processes.

Absolute cross sections have been measured for electron-impact dissociative excitation and ionization of the helium-hydride ion (HeH+) leading to the formation of helium ions Heq+ (q = 1–2). Measurements have been performed for electron energies ranging from the respective thresholds up to 2.5 keV. For He+ production, the maximum absolute cross section for dissociative excitation is found to be (2.5 ± 0.2) ×10−17 cm2 (around 40 eV), while for dissociative ionization, it is found to be (2.1 ± 0.1) ×10−17 cm2 (around 135 eV). For He2+ production, only the inclusive absolute cross section is presented, without attempting to isolate any distinct contribution, and it is measured to be (2.6 ± 0.2) ×10−19 cm2 (around the maximum, 195 eV). Appearance energies for He+ and He2+ are determined to be (11.2 ± 0.5) eV and (66.5 ± 1.0) eV, respectively. Kinetic energy release and angular distributions are obtained, at specific incident electron energies.

Absolute cross sections for electron impact single and multiple ionization of C+, N+ and O+ ions leading to the formation of Cq + (q = 2-4), Nq + (q = 2-5) and Oq + (q = 2-5) are reported. The animated crossed beam method is applied in the energy range extending from the respective thresholds up to 2.5 keV. The concerned target ions belong to the second row of the periodic table, with configurations 2s22px (x = 1-3). The maximum cross sections for the multiply charged products Cq + are found to be in the range from 2.3× 10-20 cm2 (for C4 +) up to 6.3× 10-17 cm2 (for C2 +); for N q + they range from 3.0× 10-22 cm2 (for N5 +) up to 5.1× 10-17 cm2 (for N 2 +) and, lastly, for Oq + they range from 5.5× 10-22 cm2 (for O5 +) up to 5.2× 10 -17 cm2 (for O2 +). The corresponding threshold energies are found to be in satisfactory agreement with spectroscopic values. The general feature of the measured cross sections is investigated. Their values for single ionization are reasonably explained by the calculations using the Coulomb-Born approximation with exchange, while those for multiple ionization are found to agree well with the semiempirical model for q = 3, but they appear to be notably overestimated by a semiempirical Bethe-Born-type formula when q > 3. © 2013 IOP Publishing Ltd.

Absolute cross sections have been measured using the crossed electron-ion beams method for electron-impact dissociation of the D(2)H(+) molecular ion yielding H(+), D(+), HD(+) and D(2)(+) fragments. The collision energy ranges from a few eV up to 2.5 keV. Around the maximum, cross sections are found to be of a similar amplitude: (3.25 +/- 0.08) x 10(-17) cm(2) for H(+), (3.56 +/- 0.15) x 10(-17) cm(2) for HD(+) and (3.33 +/- 0.11) x 10(-17) cm(2) for D(2)(+), except for D(+) for which the maximum cross section is (4.62 +/- 0.09) x 10(-17) cm(2). Individual contributions for dissociative excitation (DE) and for dissociative ionization (DI) are determined for each product. Close analysis of present data brings into evidence isotope effects in the fragmentation pattern of the D(2)H(+) target. Ejection of the lightest isotope is generally favoured: for resonant DE (H(+) over D(+)), for DE (molecular ions D(2)(+) and HD(+), associated with ejection of H and D, respectively) and for dissociative ionization, but not for H(+) and D(+) produced via direct dissociative excitation. Present DE cross sections for D(2)H(+) are found to be significantly lower than those measured for D(3)(+), although those of DI agree well together.