A Guided-Ion Beam Study of the O⁺(⁴S) + NH₃ System at Hyperthermal Energies

Abstract

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Reexamination of ionospheric chemistry: high temperature kinetics, internal energy dependences, unusual isomers, and corrections

“…The low range can be extended downward in other laboratories by the CRESU and trap techniques. [14][15][16][17][18][19] While going to lower temperatures helps in interpreting mechanisms, it is more important for interstellar chemistry than for ionospheric chemistry.…”

“…However, other laboratories are better at such studies. 19,[22][23][24][25][26] Reactivity of two unusual peroxide isomers will be presented, namely NOO 1 and ONOO À . While these ions were discovered elsewhere, 27,28 the previous experiments were not able to study the chemistry of these species or in the case of NOO 1 to unambiguously determine its structure.…”

Luminescence Measurements of the Hyperthermal Reactions of N/N+ + NH3

“…For the cation, charge exchange and hydrogen abstraction to produce NH (X) is exothermic by 2.1 eV (eq ), while NH (A) is endothermic by 1.6 eV, or 6.5 eV lower than CID (eq ). While there was only some evidence of hydrogen abstraction in the guided ion beam experiment of O + + NH 3 complicated by the same m / q ratio of NH 3 + and OH + , hydrogen extraction can be elucidated by comparison to similar collision systems studied by Ottinger and Kowalski, namely, N + /N + CH 4 and C + /C + NH 3 . They found that, while the first set of reactions did show evidence of hydrogen abstraction forming NH (A), the second for neutral C did not produce CH (A).…”

“…While this is also true of the cation, the energy dependence of charge exchange in these type of systems needs to be considered. Previous experiments of O + + NH 3 and Xe + + NH 3 measured the absolute cross section of charged products. , While NH (A) produces the largest emission product, the largest product overall is purely charge exchange as it is an exothermic process. At 0.1 eV, the absolute cross sections measured were 60 × 10 –16 and 200 × 10 –16 cm 2 , respectively, for O + and Xe + .…”

“…Investigations have been carried out with ammonia with near-thermal metastable species (Ar*/Kr*/Xe*) as well as with ground states of the corresponding cations. − For the cations, the dominant reaction is charge exchange producing NH 3 + as it is an exothermic process, but a large fraction of reactions undergo collision-induced dissociation (CID) producing NH (A) and other excited-state species, which have been observed in chemiluminescence experiments. These reactions of ammonia have also been extended to H + , He + , and O + , producing similar products. − However, while nitrogen is a significant atomic component of the LEO atmosphere, there have been no investigations of the N + NH 3 collision system. Equations through describe some of the likely reactions along with their respective energetics.…”