Optical emission in the dissociation of ammonia by low energy He+ ions

Drozdowski, R.; Werbowy, S.; Sobolewski, Ł.M.; Kowalski, A.

doi:10.1140/epjd/e2017-70732-7

Cited by 2 publications

(10 citation statements)

References 63 publications

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“…Similar results were obtained by Drozdowski et al for the emission products of He + + ND 3 . 11 A similar cross section of about 1 × 10 −18 cm 2 was found at 100 eV (COM), although in this case they observed a peak in the signal followed by a small decrease in the emission cross section, whereas Xe + /Kr + only show a plateau in the emission cross section. The previous authors carefully considered the potentially lost luminescence signal due to the radiative lifetime of products as the collision products moved in the laboratory frame.…”

Section: Discussionsupporting

confidence: 59%

“…Signatures from this emission were also not observed in higher quality spectra appearing in the literature. 11,41,42 Our previous work has also observed NH + (A−X) emissions following the collision of NH 3 with Ar + and Xe 2+ . 5 In this work, this feature was also observed using N 2 + as the collision ion.…”

Section: Resultsmentioning

confidence: 97%

“…5 Drozdowski et al found a slightly cooler rotational temperature for ND (A−X) of 3500 K for the H + + ND 3 and 4000 K for He + + NH 3 . 10,11 This same rotational temperature was used for the 0−0 band c−a transition, but the spectra were not sensitive to this parameter due to the limited spectral resolution. For the case of H + and He + collision systems, lower temperatures for NH (c−a) were observed around 1000 K.…”

Section: Resultsmentioning

confidence: 99%

“…The NH 2 (A ̃) state does fluoresce to the (X) state in the region of 300− 500 nm, but its lifetime of about 10 μs 43 would make it unlikely to be observed here nor was it from He + −ammonia collisions. 11 In either case, the higher reaction energy would explain the increasing emission cross sections as the collision energy is increased. Like the NH emissions, the neutral collision systems result in smaller emission cross sections for H-α than the cations.…”

Section: Discussionmentioning

confidence: 99%

“…The amount of NH (c) produced here is consistent with that of the Drozdowski He + + ND 3 system, where the energy dependence of the ND (c−a) is about 25% of the total ND emissions at 100 eV and above. 11 In that system, the branching ratio between the (c) and (A) states were rationalized using the calculation of Runau et al of the NH 3 SCF potential surfaces. 44 The (A) excited state of ammonia splits into singlet ( 1 A 2 ′) and triplet components ( 3 A 2 ″), and dissociation to NH + H 2 leads to c ( 1 Π) and A ( 3 Π), respectively.…”

Section: Discussionmentioning

confidence: 99%

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

Hause¹,

Prince²,

Bemish³

2023

J. Phys. Chem. A

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Chemiluminescence from a system of collisions, N + / N/Kr + /Kr/Xe + /Xe + NH 3 , at collision energies between 10 and 170 eV (center of mass, COM), was measured in the spectral range 300−1000 nm. The energy dependence of the emission excitation cross sections was quantified, and molecular signatures were fit to known spectroscopic constants to determine vibrational-state populations. For both N and N + collision species, the strongest features were assigned to emissions from NH (A−X) and the atomic hydrogen Balmer series. For each of the spectra resulting from collisions with primary cations, the NH (A−X) emissions had the largest cross sections reaching values of (1.0−1.5) × 10 −18 cm 2 by 100 eV. Additional features originating from atomic nitrogen and NH (c−a) emissions were also observed. The NH (c−a) emissions accounted for about 8%, 13%, and 15% for total excited populations in collisions with Xe + , N + , and Kr + , respectively. These transitions were consistent with short-range interactions resulting in collision-induced dissociation of the NH 3 molecule with apparent energy thresholds between 20 and 30 eV and emission cross sections decreasing with ion mass. Evidence of charge exchange in the N + + NH 3 collisions was observed in the resulting spectra as broad transitions between 420 and 480 nm and were assigned to NH + emitting from the (B) state. Differences between the spectra were observed as changes in the emission signal with the neutral collisions producing only 30% or 65% of the NH (A−X) emission cross sections compared to the cation results for xenon and krypton, respectively. For N and N + , NH (A) was created in equal amounts at lower collision energies, but the emission for the neutral system increases above that of the cation at collision energies greater than 80 eV COM. In both cases, the threshold energy for appearance was below 10 eV, suggesting an additional pathway for NH (A) formation, namely, hydrogen abstraction or charge exchange and abstraction for the N and N + , respectively. In all cases, the neutral NH (c−a) emission intensity was similar between neutral and cation pairs. The H-α emission line (n = 3−2) decreased to about 10%, 33%, and 50% of the corresponding cation spectra for xenon, krypton, and nitrogen, respectively.

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Section: Discussionsupporting

confidence: 59%