Collision-induced dissociation of 10 keV N2+ ions: Evidence for predissociation of the C2Σu+ state

Fournier, P. G.; Runstraat, C.A. van de; Govers, T.R.; Schopman, Joop; Heer, F. J. de; Los, J.

doi:10.1016/0009-2614(71)80259-2

Cited by 49 publications

(18 citation statements)

References 7 publications

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“…The experimental results obtained through collision induced dissociation of N 2 + [6] as well as by the study of the electron impact ionization efficiency curve of N + from N 2 [24], are found in good agreement with the structure corresponding to the C 2 Σ u + state of N 2 + . Wankenne et al [24] brought evidence of an enhancement of the signal observed at 24.575 eV, when He is added to the N 2 beam.…”

Section: Dissociation Limit At (2434 ± 020) Evsupporting

confidence: 72%

“…In both experiments a pronounced discrete structure was observed and ascribed to the predissociation of the C 2 Σ u + state of N 2 + [6]. In the unimolecular dissociation experiment [7] an additional structure and a strong isotope effect were observed.…”

Section: Introductionmentioning

confidence: 89%

“…In the fifth column of table 2 are listed the total kinetic energy values (i.e., twice the measured values) which could be directly correlated with spectroscopic data. In the same table 2 the most significant previously published results [6,7,24] are collected.…”

Section: Kinetic Energy Measurementsmentioning

confidence: 99%

“…Schopman et al [6,7] analysed under high resolution the laboratory velocity distribution of the N + fragments formed by the impact of a 10 keV N 2 + beam on He [6] and at a residual gas pressure [7]. In both experiments a pronounced discrete structure was observed and ascribed to the predissociation of the C 2 Σ u + state of N 2 + [6].…”

Section: Introductionmentioning

confidence: 99%

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The dissociative ionization of nitrogen

et al. 1975

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Energy distributions and appearance potentials of N ions produced by low-energy electron impact on N2 have been measured. At least five dissociation limits were detected either directly in the ionization efficiency curves of N or by extrapolation of the 1/2 slope straight lines drawn through the kinetic energy versus appearance potential energy diagram. Fine structure observed at low ion energy has been interpreted by the predissociation of at least two N 2 excited states one of which being the well-known C 2 Σ u + state. One of the others could be a 2 Π u state pre-dissociated to the dissociation limit at 24.34 eV. Close correlation between the results of the present work and photoelectron spectroscopic observations could be done over the electron energy range between 24.3 eV and 36 eV and assignments are discussed in detail.

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Section: Dissociation Limit At (2434 ± 020) Evsupporting

confidence: 72%

Section: Introductionmentioning

confidence: 89%

Section: Kinetic Energy Measurementsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The dissociative ionization of nitrogen

et al. 1975

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“…In fact, in most of the investigated cases, this excitation results from an electron capture by the molecular ion at large impact parameter to a dissociative [7] or predissociative state [8]. Such processes, referred to as the electronic mechanism (EM), somewhat analogous to photodissociation, do not require, in contrast to mechanism IM, a large deflection of the CM of the molecule.…”

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confidence: 99%

Analysis of Collision Induced Dissociation ofNa2+Molecular Ions

et al. 1996

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A full analysis of the collision induced dissociation of a diatomic molecular ion is presented for the first time. The experiment is essentially based on the simultaneous measurement of the momenta of the two fragments. This technique applied to the collision of Na 2 1 with a helium target reveals, at keV collision energies, the competition between two dissociation mechanisms: an impulsive mechanism when the target hits one Na 1 core in a close encounter and an electronic mechanism when dissociation occurs after excitation of repulsive or weakly bound states. [S0031-9007(96)00952-0] PACS numbers: 34.50.Pi, 34.50.LfCollision induced dissociation (CID) of diatomic molecules is an example of a three body interaction which is not yet fully understood. Back in the sixties, the study of CID of H 2 1 molecules was initially motivated by the need to produce fast H atoms for heating plasma of interest for thermonuclear fusion. Then, during the seventies, an intense activity developed when it was demonstrated that accurate measurements of momentum distributions of dissociation fragments produced in fast collisions were a powerful tool to access the spectroscopy of molecular ions with meV accuracy [1]. Termed "translational spectroscopy," this technique allows for such an accuracy, owing to the magnification introduced by the laboratory-to-center-of-mass (CM) transformation of the momentum distribution of the fragments. Our knowledge of this field is well summarized in the review of Los and Govers [2]. In the keV energy range and for the investigated systems, the collision time is much shorter than the dissociation time of the molecule, allowing approximations in terms of "two step" mechanisms. In the first step, the molecule is excited into an unstable state. In the second step, dissociation occurs far from the perturbing partner of the collision. As first proposed by Durup [3], two classes of mechanisms have been considered, depending on the first step of the collision.(i) A close encounter between one atomic core of the molecule and the target atom, the other atomic core remaining spectator, leads to a large stretching of the molecule resulting in vibrational excitation, increasing with the scattering angle [4]. Such a mechanism, hereafter referred to as the impulse mechanism (IM), has been identified by measuring the energy losses undergone by a molecular projectile as a function of the scattering angle [5]. In such a collision induced vibrational excitation, the molecule dissociates when the energy transfer is large enough. Although often invoked, this dissociation mechanism has never been directly observed. Notice that such a binary impulse mechanism has already been invoked as an initial step for reactive collision processes at moderate energy [6].(ii) In a more distant collision, the target may primarily interact with the electron cloud of the molecule which can be electronically excited into a dissociative state. In fact, in most of the investigated cases, this excitation results from an electron capture by the mol...

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Role of Excited States in Ion‐Neutral Collisions

Tiernan

Lifshitz

1981

Advances in Chemical Physics

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Collision-induced dissociation of 10 keV N2+ ions: Evidence for predissociation of the C2Σu+ state

Cited by 49 publications

References 7 publications

The dissociative ionization of nitrogen

The dissociative ionization of nitrogen

Analysis of Collision Induced Dissociation ofNa2+Molecular Ions

Role of Excited States in Ion‐Neutral Collisions

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