Erratum: Collisional excitation of NH3 by atomic and molecular hydrogen

Bouhafs, Nezha; Daniel, F.; Dumouchel, F.; Lique, François; Wiesenfeld, Laurent; Fauré, Alexandre

doi:10.1093/mnras/sty3487

Cited by 3 publications

(2 citation statements)

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“…Cross sections are very significantly larger for collisions with ortho-H 2 than with para-H 2 , 2 = 0, an expected result , due to the non isotropy of H 2 (static quadrupole and anisotropic polarizabilty of H 2 , allowing for anisotropic long-distance interaction). The effect is particularly large, but remains compatible with other collisions with a polar molecule [39][40][41] . Here, however, vibrational quenching cross sections gain another order of magnitude with including both 2 = 1 and 2 = 3 ortho rotational levels of H 2 , remaining with initial conditions at 2 = 1.…”

supporting

confidence: 59%

Quantum nature of molecular vibrational quenching: Water - molecular hydrogen collisions

Wiesenfeld

2021

Preprint

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Rates of conversions of molecular internal energy to and from kinetic energy by means of molecular collision allows to compute collisional line shapes and transport properties of gases. Knowledge of ro-vibrational quenching rates is necessary to connect spectral observations to physical properties of warm astrophysical gasses, including exo-atmospheres. For a system of paramount importance in this context, the vibrational bending mode quenching of H 2 O by H 2 , we show here that exchange of vibrational to rotational and kinetic energy remains a quantum process, despite the large numbers of quantum levels involved and the large vibrational energy transfer. The excitation of the quantized rotor of the projectile is by far the most effective ro-vibrational quenching path of water. To do so, we use a fully quantum first principle computation, potential and dynamics, converging it at all stages, in a full coupled channel formalisms. We present here rates for the quenching of the first bending mode of ortho-H 2 O by ortho H 2 , up to 500 K, in a fully converged coupled channels formalism.

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supporting

confidence: 59%

Quantum nature of molecular vibrational quenching: Water - molecular hydrogen collisions

Wiesenfeld

2021

Preprint

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“…A similar C 3v symmetric top structure was determined from MW spectra for the NH 3 -Cl 2 , 17 NH 3 -Br 2 , 18 NH 3 -ClF, 19 and NH 3 -H 2 20 complexes. The latter one was also a subject of numerous theoretical and experimental investigations [21][22][23][24][25][26] due to its astrophysical relevance.…”

Section: Article Scitationorg/journal/jcpmentioning

confidence: 99%

Ab initio potential energy surface and microwave spectrum of the NH3–N2 van der Waals complex

Surin

Tarabukin

Hermanns

et al. 2020

The Journal of Chemical Physics

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We present a five-dimensional intermolecular potential energy surface (PES) of the NH3–N2 complex, bound state calculations, and new microwave (MW) measurements that provide information on the structure of this complex and a critical test of the potential. Ab initio calculations were carried out using the explicitly correlated coupled cluster [CCSD(T)-F12a] approach with the augmented correlation-consistent aug-cc-pVTZ basis set. The global minimum of the PES corresponds to a configuration in which the angle between the NH3 symmetry axis and the intermolecular axis is 58.7° with the N atom of the NH3 unit closest to the N2 unit, which is nearly parallel to the NH3 symmetry axis. The intermolecular distance is 7.01 a0, and the binding energy De is 250.6 cm–1. The bound rovibrational levels of the four nuclear spin isomers of the complex, which are formed when ortho/para (o/p)-NH3 combines with (o/p)-N2, were calculated on this intermolecular potential surface. The computed dissociation energies D0 are 144.91 cm−1, 146.50 cm−1, 152.29 cm−1, and 154.64 cm−1 for (o)-NH3–(o)-N2, (o)-NH3–(p)-N2, (p)-NH3–(o)-N2, and (p)-NH3–(p)-N2, respectively. Guided by these calculations, the pure rotational transitions of the NH3–N2 van der Waals complex were observed in the frequency range of 13–27 GHz using the chirped-pulse Fourier-transform MW technique. A complicated hyperfine structure due to three quadrupole 14N nuclei was partly resolved and examined for all four nuclear spin isomers of the complex. Newly obtained data definitively established the K values (the projection of the angular momentum J on the intermolecular axis) for the lowest states of the different NH3–N2 nuclear spin isomers.

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Quantum nature of molecular vibrational quenching: Water–molecular hydrogen collisions

Wiesenfeld

2021

The Journal of Chemical Physics

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Rates of conversions of molecular internal energy to and from kinetic energy by means of molecular collision allow us to compute collisional line shapes and transport properties of gases. Knowledge of ro-vibrational quenching rates is necessary to connect spectral observations to physical properties of warm astrophysical gasses, including exo-atmospheres. For a system of paramount importance in this context, the vibrational bending mode quenching of H2O by H2, we show here that the exchange of vibrational to rotational and kinetic energy remains a quantum process, despite the large numbers of quantum levels involved and the large vibrational energy transfer. The excitation of the quantized rotor of the projectile is by far the most effective ro-vibrational quenching path of water. To do so, we use a fully quantum first-principles computation, potential and dynamics, converging it at all stages, in a full coupled channel formalism. We present here rates for the quenching of the first bending mode of ortho-H2O by ortho-H2, up to 500 K, in a fully converged coupled channel formalism.

show abstract

Erratum: Collisional excitation of NH3 by atomic and molecular hydrogen

Cited by 3 publications

References 1 publication

Quantum nature of molecular vibrational quenching: Water - molecular hydrogen collisions

Quantum nature of molecular vibrational quenching: Water - molecular hydrogen collisions

Ab initio potential energy surface and microwave spectrum of the NH3–N2 van der Waals complex

Quantum nature of molecular vibrational quenching: Water–molecular hydrogen collisions

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