Experimental study of the Penning ionization of the H2O molecule by He* (23S, 21S) metastable atoms

Arfa, M. Ben; Coz, G. Le; Sinou, G.; Nadan, A. Le; Tuffin, F.; Tannous, C.

doi:10.1088/0953-4075/27/12/012

Cited by 10 publications

(5 citation statements)

References 33 publications

(7 reference statements)

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“…Also in these cases we recorded negative energy shifts having a bigger value, indicating a more attractive behavior in the case of He * -M collisions respect to Ne * -M collisions (with M = H2S, NH3). This observation is in fairly good agreement with previous results obtained by Ohno et al [27] and Ben Arfa et al [39] P2 state), which is the fundamental physical property of the partners, enhancing the attractive interaction behavior of the potential energy surfaces [22]. As already discussed in previous papers [22,23], by a simple analysis of obtained PIES spectra, in the case of H2O + -1b1, H2S + -2b1, and NH3 + shift, εmax, from the change in position of the maximum of peak but also the shift between the electron energy value where the peak intensity drops down to 44% of its maximum at the lower energy side, εA, with respect to the nominal energy, ε0 [40].…”

Section: Resultssupporting

confidence: 94%

The Possible Role of Penning Ionization Processes in Planetary Atmospheres

2015

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Abstract:In this paper we suggest Penning ionization as an important route of formation for ionic species in upper planetary atmospheres. Our goal is to provide relevant tools to researchers working on kinetic models of atmospheric interest, in order to include Penning ionizations in their calculations as fast processes promoting reactions that cannot be neglected. Ions are extremely important for the transmission of radio and satellite signals, and they govern the chemistry of planetary ionospheres. Molecular ions have also been detected in comet tails. In this paper recent experimental results concerning production of simple ionic species of atmospheric interest are presented and discussed. Such results concern the formation of free ions in collisional ionization of H2O, H2S, and NH3 induced by highly excited species (Penning ionization) as metastable noble gas atoms. The effect of Penning ionization still has not been considered in the modeling of terrestrial and extraterrestrial objects so far, even, though metastable helium is formed by radiative recombination of He + ions with electrons. Because helium is the second most abundant element of the universe, Penning ionization of atomic or molecular species by He * (2 3 S1) is plausibly an active route of ionization in relatively dense environments exposed to cosmic rays. OPEN ACCESSAtmosphere 2015, 6 300

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Section: Resultssupporting

confidence: 94%

The Possible Role of Penning Ionization Processes in Planetary Atmospheres

2015

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“…The experimental apparatus has been fully described elsewhere by Ben Arfa et al [31]. The metastable projectile beam and the target one are formed by effusion through a multi-capillary array and cross at right angles.…”

Section: Methodsmentioning

confidence: 99%

The interaction of excited He, Ar and Ne metastable atoms with the CF₂Cl₂molecule

Cherid¹,

Arfa²,

Khodja³

2004

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

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We studied Penning ionization of the CF2Cl2 molecule by neon and helium metastable atoms. In the case of the neon ionizing particle, we measured the electron kinetic energy as well as mass spectra; for helium metastable atoms, only the mass spectrum was recorded. We, therefore, obtained the branching ratios for the heavy charged particles produced in both interactions. In this report we will discuss the mechanism involved in the production of metastable halogen atoms in the dielectric barrier discharge further to the use of rare gases/CF2Cl2 mixtures. We show that this process needs a two-stage reaction. Ground state free halogen atoms are formed over the first stage by Penning ionization, charge transfer, dissociate excitation and ionization. Therefore, metastable halogen atoms can be produced by excitation transfer process in the second stage through interaction with metastable rare gas atoms.

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“…In the excitation transfer process, this is understood to be the result of the long life time of the intermediate Rydberg state allowing the molecule to rotate before autoionization, but in attractive collision systems, the isotropic angular distribution is explained as the effect of the spiralling classical collision trajectory. It is well established that an attractive collision system leads to a broad vibronic band in the electron energy spectrum, as in the case of He * -H 2 O (Cermak 1977, Ben Arfa et al 1994. So the observed non-Franck-Condon vibrational population of the X band and the isotropic angular behaviour of the additional vibrational structures rationalise the hypothesis of the excitation transfer in the He * -CO collision.…”

Section: Resultsmentioning

confidence: 58%

Autoionization process in Penning ionization of the CO molecule by helium atoms in triplet metastable state

Lescop

Arfa

Cherid

et al. 1997

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

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In this paper, we investigate the Penning ionization of the CO molecule by helium atoms in metastable states. The energy distribution spectrum of electrons related to the CO + (X 2 + ) ion state shows a deviation of the vibrational population from the predicted Franck-Condon factors. The angular distribution measurements exhibit an intensity increasing towards the backward direction for the v = 0 level, while the corresponding angular distributions of the higher vibrational levels (v = 2, 3 and 4) are isotropic. To explain these results, an excitation transfer process between the colliding particles is suggested. This gives rise to a CO molecule either in a doubly excited Rydberg state converging to CO + (D 2 ) or in the σ * quasi-bound state (shape resonance). Autoionization of the doubly excited state (CO * * ) leads to the population of vibrational levels which are forbidden by the Franck-Condon principle in the case of a direct processes.

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Experimental study of the Penning ionization of the H₂O molecule by He* (2³S, 2¹S) metastable atoms

Cited by 10 publications

References 33 publications

The Possible Role of Penning Ionization Processes in Planetary Atmospheres

The Possible Role of Penning Ionization Processes in Planetary Atmospheres

The interaction of excited He, Ar and Ne metastable atoms with the CF₂Cl₂molecule

Autoionization process in Penning ionization of the CO molecule by helium atoms in triplet metastable state

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Experimental study of the Penning ionization of the H2O molecule by He* (23S, 21S) metastable atoms

Cited by 10 publications

References 33 publications

The Possible Role of Penning Ionization Processes in Planetary Atmospheres

The Possible Role of Penning Ionization Processes in Planetary Atmospheres

The interaction of excited He, Ar and Ne metastable atoms with the CF2Cl2molecule

Autoionization process in Penning ionization of the CO molecule by helium atoms in triplet metastable state

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Experimental study of the Penning ionization of the H₂O molecule by He* (2³S, 2¹S) metastable atoms

The interaction of excited He, Ar and Ne metastable atoms with the CF₂Cl₂molecule