Translational energy spectroscopy of N+ and O+ in collision with O2

Lee, A.R.; Enos, C.S.; Brenton, A.G.

doi:10.1016/0301-0104(91)80135-5

Cited by 13 publications

(2 citation statements)

References 11 publications

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“…In several N + reaction studies, dissociative ionization of N 2 by electron impact is used to produce excited N + , but only a fraction of the N + population is in a metastable state. In the first ones, , a 15% population of the first metastable state 1 D is estimated, with the remaining population in the ground state 3 P. In another one, an unknown mixture of 1 D/ 1 S/ 5 S metastable states is believed to constitute 30% of the population, with the remaining 70% in the ground state 3 P. This last work 27 is, to our knowledge, a unique study of the reaction of metastable N + ions with methane. For the reaction of N + metastable ions, they report a total rate constant equal to the rate constant of ground-state ions, 1.1 × 10 -9 cm 3 s -1 , and the inferred branching ratio found between the four main products CH 3 + /CH 4 + /HNC + /HCNH + is 0.2:0.1:0.3:0.4 …”

Section: Introductionmentioning

confidence: 95%

¹⁵N⁺ + CD₄ and O⁺ + ¹³CO₂ State-Selected Ion−Molecule Reactions Relevant to the Chemistry of Planetary Ionospheres

et al. 2004

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The dissociative photoionization of N2 and O2 by synchrotron radiation in coincidence with threshold photoelectrons is used to produce state-selected N+ and O+ atomic ions to study their reactivity. A pure selection of their ground state, N+(3P) and O+(4S), or excited states, N+(1D), O+(2D), and O+(2P), is obtained by the choice of the photon energy and by further discrimination of atomic ions produced with translational recoil energy. Both reactions studied, 15N+ + CD4 and O+ + 13CO2, are of major importance for the chemistry of Titan, Mars, and Venus' ionospheres and are strongly affected by excitation of the parent atomic ion. For the reaction of N+ with methane, DCN+ and DCND+ products coming from the decomposition of a long-lived complex are surprisingly not much sensitive to the N+ excitation, whereas the branching ratio between the dissociative charge-transfer channel, leading to CD3 +, which is the main product for the ground-state reaction, and the nondissociative charge-transfer channel, leading to CD4 +, is completely inverted in favor of the latter when N+ is excited into the 1D state. This unanticipated result can be well understood by the spin−orbit selection rule in the N+ recombination. For the reaction of O+ with carbon dioxide, the reactive channel producing O2 +, which dominates for the ground-state reaction for thermal collision energies, is completely displaced in favor of the endothermic charge-transfer channel leading to CO2 + if either collision energy or O+ internal energy is brought to the system. The O+(2P) metastable state has a larger reaction cross section than the lower 2D metastable state. Owing to the long lifetime of the N+ and O+ metastable states studied here and to their very specific reactivity, they should be individually considered in the models describing the planetary ionospheric chemistry.

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Section: Introductionmentioning

confidence: 95%

¹⁵N⁺ + CD₄ and O⁺ + ¹³CO₂ State-Selected Ion−Molecule Reactions Relevant to the Chemistry of Planetary Ionospheres

et al. 2004

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“…Among the three metastable states of N + , only the N + ( 1 D) state has already been clearly identified in the N 2 dissociative photoionization (Morioka et al 1984, Eland and Duerr 1998. By 100 eV electron impact on N 2 , it has been shown that N + ( 1 D) represents about 15% of the total N + ion yield (Lee et al 1991). In this study, we propose to measure precisely the branching ratio between the different dissociation channels as a function of N + 2 internal energy by exciting N 2 in the 24-32 eV photon energy range.…”

Section: Introductionmentioning

confidence: 99%

Dissociative photoionization of N₂in the 24–32 eV photon energy range

Nicolas

Alcaraz

Thissen

et al. 2003

J. Phys. B: At. Mol. Opt. Phys.

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Dissociative photoionization of N2 is studied with synchrotron radiation in the 24–32 eV photon energy range. Branching ratios between the different dissociation limits are measured from coincidence time of flight ion spectra threshold photoelectron–photoion coincidence recorded for state-selected N2+ parent ions. In this energy range, N2+ molecular ions are observed to dissociate only towards the three lowest dissociation limits. Dissociations towards the second and third ones, which correspond to the formation of N+(1D) and N(2D) metastable states, respectively, occur right from their thermochemical onsets. From the second dissociation limit energy up to the third one, the N+(1D) + N(4S)/N+(3P) + N(4S) branching ratio is almost constant and equal to 0.6:0.4, except at the energy of the C 2 Σ u+ (v = 12) state, where this branching ratio is found to be equal to 0.5:0.5. From the third dissociation limit onset, N2+ ions fragment only towards this limit. Possible dissociation mechanisms are discussed, involving a spin–orbit coupling between doublet and quartet states of N2+ to produce N+(1D) + N(4S) and a direct dissociation to produce N+(3P) + N(2D). No dissociation towards the other limits has been observed, in particular to produce the N+(1S), N+(5S) and N(2P) metastable states.

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Energy studies of atomic atmospheric ions in collisions with molecular nitrogen and oxygen

Enos

Lee

Brenton

1991

Org. Mass Spectrom.

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Studies of internal energy changes between the partners in ion-molecule collisions can be facilitated by highresolution translational energy spectroscopy. Collisions of keV H', N + and 0' on molecular nitrogen and oxygen have shown that for 30 reaction channels all are consistent with spin conservation, which has not been generally acknowledged in previous studies. Estimations of the fractional metastable composition in each ion beam have also been made.

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Translational energy spectroscopy of N+ and O+ in collision with O2

Cited by 13 publications

References 11 publications

¹⁵N⁺ + CD₄ and O⁺ + ¹³CO₂ State-Selected Ion−Molecule Reactions Relevant to the Chemistry of Planetary Ionospheres

¹⁵N⁺ + CD₄ and O⁺ + ¹³CO₂ State-Selected Ion−Molecule Reactions Relevant to the Chemistry of Planetary Ionospheres

Dissociative photoionization of N₂in the 24–32 eV photon energy range

Energy studies of atomic atmospheric ions in collisions with molecular nitrogen and oxygen

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Translational energy spectroscopy of N+ and O+ in collision with O2

Cited by 13 publications

References 11 publications

15N+ + CD4 and O+ + 13CO2 State-Selected Ion−Molecule Reactions Relevant to the Chemistry of Planetary Ionospheres

15N+ + CD4 and O+ + 13CO2 State-Selected Ion−Molecule Reactions Relevant to the Chemistry of Planetary Ionospheres

Dissociative photoionization of N2in the 24–32 eV photon energy range

Energy studies of atomic atmospheric ions in collisions with molecular nitrogen and oxygen

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¹⁵N⁺ + CD₄ and O⁺ + ¹³CO₂ State-Selected Ion−Molecule Reactions Relevant to the Chemistry of Planetary Ionospheres

¹⁵N⁺ + CD₄ and O⁺ + ¹³CO₂ State-Selected Ion−Molecule Reactions Relevant to the Chemistry of Planetary Ionospheres

Dissociative photoionization of N₂in the 24–32 eV photon energy range