Inelastic scattering dynamics of ortho and para hydronium ions, o-H3O+ and p-H3O+, with He at low temperature

Hanini, Houda El; Najar, Faouzi; Naouai, Manel; Jaı̈dane, N.

doi:10.1039/c9cp01889a

Cited by 9 publications

(29 citation statements)

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“…The global well depth, calculated for the H 3 O + -He system is about 354.53 cm −1 . The anisotropy of the PES in the work of El Hanini et al 21 was strong at short and intermediate radial distances. It is however well established that He is a poor substitute for H 2 in the case of collisional excitation of interstellar ions 26 .…”

Section: Introductionmentioning

confidence: 78%

“…Hence rate coefficients for rotational excitation of H 3 O + are missing for interpreting the observations in the ISM. Having the accurate abundance of H 3 O + can also be used as an indirect method to determine the abundance of interstellar water 21 . The theoretical approaches for bimolecular collision-dynamics calculations require the knowledge of the full intermolecular potential energy surface (PES), which ideally contains all the information about the interaction of the molecules nuclei and electrons during the collision 22 .…”

Section: Introductionmentioning

confidence: 99%

“…The electron-impact excitation of H 3 O + was studied by Faure & Tennyson 23 by combining the R-matrix theory with the adiabatic-nuclei-rotation approximation. The rotational excitation of H 3 O + cations was also studied recently in collision with He atoms, as a template for the H 2 molecule 21 . The authors of this work determined the rotational rate coefficients both for paraand ortho-H 3 O + for kinetic temperatures in the range 5 -50 K using the close-coupling (CC) approach.…”

Section: Introductionmentioning

confidence: 99%

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An accurate 5D potential energy surface for H3O+–H2 interaction

Demes

Lique

Fauré

2020

The Journal of Chemical Physics

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Section: Introductionmentioning

confidence: 78%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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An accurate 5D potential energy surface for H3O+–H2 interaction

Demes

Lique

Fauré

2020

The Journal of Chemical Physics

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“…The accuracy of the interaction potentials generated using the methodology elaborated above has been assessed in our previous works (Najar et al 2017;El Hanini et al 2019). We display in Fig.…”

Section: Potential Energy Surfacementioning

confidence: 99%

State-to-state inelastic rate coefficients of phosphine in collision with He at low to moderate temperature

Badri

Najar

Bop

et al. 2020

Monthly Notices of the Royal Astronomical Society

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Several phosphorus-bearing molecules, such as the phosphine of interest here, have been detected in astrophysical media. With the aim of satisfying the precision required by the astrophysical community, we report the rate coefficients of PH 3 in collision with helium from low to moderate temperature. To this end, we constructed the first three-dimensional potential energy surface (3D-PES) of the PH 3-He van der Waals complex, which governs the nuclear motions. The 3D-PES was worked out by means of the standard coupled cluster with single, double and non-iterative triple excitation approach, in conjunction with the aug-cc-pVQZ basis set and complemented by mid bond functions. This 3D-PES presents a well of 34.92 cm −1 at {R, θ , } = {5.76a 0 , 90 • , 60 • }. Afterwards, we incorporated this 3D-PES into time-independent close-coupling quantum dynamical computations to derive the inelastic cross-sections of rotational excitation of (ortho-) para-PH 3 after collision with He up to (1000) 500 cm −1. Subsequently, we evaluated the rate coefficients for temperatures up to (100 K) 50 K populating the (41) 42 low-lying rotational levels of (ortho-) para-PH 3. These data were derived by averaging the cross-sections thermally over the Maxwell-Boltzmann velocity distribution. No general propensity rules are found. We also performed a comparison with the rates for NH 3-He. Differences are observed that invalidate the use of NH 3 rates for deducing accurate abundances of phosphine in cold astrophysical media. Our results should be of great help in determining accurate PH 3 abundances and, more generally, constraining the interstellar PH 3 chemistry better.

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“…The collisional excitation of H 3 O + by He atoms (as a template for H 2 ) was recently studied by El Hanini et al (2019). It is worth to mention however that He is a factor of 5 less abundant than H 2 .…”

Section: Introductionmentioning

confidence: 99%

Rotational excitation of H3O+ cations by para-H2: improved collisional data at low temperatures

Demes

Lique

Fauré

et al. 2021

Monthly Notices of the Royal Astronomical Society

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The hydronium cation plays a crucial role in interstellar oxygen and water chemistry. While its spectroscopy was extensively investigated earlier, the collisional excitation of H 3 O + is not well studied yet.In this work we present state-to-state collisional data for rotational de-excitation of both ℎ -and -H 3 O + due to -H 2 impact. The cross sections are calculated within the close-coupling formalism using our recent, highly accurate rigid-rotor potential energy surface for this collision system. The corresponding thermal rate coefficients are calculated up to 100 K. For -H 3 O + the lowest 20 rotation-inversion states were considered in the calculations, while for ℎ -H 3 O + the lowest 11 states are involved (up to ≤ 5), so all levels with rotational energy below 420 K (292 cm −1 ) are studied.In order to analyse the impact of the new collisional rates on the excitation of H 3 O + in astrophysical environments radiative transfer calculations are also provided. The most relevant emission lines from an astrophysical point of view are studied, taking into account the transitions at 307, 365, 389 and 396 GHz. We show that our new collisional data have a non-negligible impact (from a few percents up to about a factor of 3) on the brightness and excitation temperatures of H 3 O + , justifying the revision of the physical conditions in the appropriate astrophysical observations. The calculated rate coefficients allow one to recalculate the column density of hydronium in interstellar clouds, which can lead to a better understanding of interstellar water and oxygen chemistry.

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Inelastic scattering dynamics of ortho and para hydronium ions, o-H₃O⁺ and p-H₃O⁺, with He at low temperature

Abstract: In this work, we investigated rotationally inelastic scattering of both hydronium ion forms, p-H3O+ and o-H3O+, colliding with a helium atom.

Cited by 9 publications

References 30 publications

An accurate 5D potential energy surface for H3O+–H2 interaction

An accurate 5D potential energy surface for H3O+–H2 interaction

State-to-state inelastic rate coefficients of phosphine in collision with He at low to moderate temperature

Rotational excitation of H3O+ cations by para-H2: improved collisional data at low temperatures

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