Reactions of H2, HD, and D2 with H2+, HD+, and D2+: Product-Channel Branching Ratios and Simple Models

Merkt, Frédéric; Höveler, Katharina; Deiglmayr, Johannes

doi:10.1021/acs.jpclett.1c03374

Cited by 11 publications

(4 citation statements)

References 48 publications

(86 reference statements)

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“…These results complement significantly the recent investigations on the other main competing destructive channels of H + 2 , HD + and D + 2 via their reactions with H 2 , HD and D 2 that produce the H + 3 , H 2 D + , D 2 H + and D + 3 triatomic ions [33], allowing to remove significant uncertainties of previous studies.…”

Section: Discussionsupporting

confidence: 84%

Dissociative recombination and rotational transitions of D+2 in collisions with slow electrons

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et al. 2022

Monthly Notices of the Royal Astronomical Society

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Rate coefficients for dissociative recombination and state-to-state rotational transitions of the D$_{2}^{+}$ ion induced by collisions with very low-energy electrons have been reported following our previous studies on HD+ and H$_{2}^{+}$. The same molecular structure data sets, excitations ($N_{i}^{+} \rightarrow$$N_{f}^{+}=N_{i}^{+}+2$ for $N_{i}^{+}=0$ to 10) and de-excitations ($N_{i}^{+}\rightarrow N_{f}^{+}=N_{i}^{+}-2$, for $N_{i}^{+}=2$ to 10) were used for collision energies ranging from 0.01 meV to 0.3 eV. Isotopic effects for dissociative recombination and rotational transitions of the vibrationally relaxed targets are presented.

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Section: Discussionsupporting

confidence: 84%

Dissociative recombination and rotational transitions of D+2 in collisions with slow electrons

Epée

Motapon

Pop

et al. 2022

Monthly Notices of the Royal Astronomical Society

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“…The Rydberg electron does not influence the reaction between the ion core and the neutral molecule taking place within the Rydberg-electron orbit, but shields the reaction system from external electric fields. With this method, we have started systematic investigations at low collision energies of the role of the charge-dipole interactions with the examples of the He + + CH 3 F [34] and He + + NH 3 /ND 3 [35] reactions, and of the charge-quadrupole interaction with the example of the H + 2 + H 2 [36][37][38][39] and He + + N 2 reactions [40]. These studies have led to the observation of large, state-specific deviations of the rate coefficients from k L at low collision energies.…”

Section: Introductionmentioning

confidence: 99%

Effects of the charge–dipole and charge–quadrupole interactions on the He⁺ + CO reaction rate coefficients at low collision energies

2022

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The reaction between He$^+$ and CO forming $\textrm{He} + \textrm{C}^+ + \textrm{O}$ has been studied at collision energies in the range between $0$ and $k_\textrm{B} \cdot 25 \, \textrm{K}$. These low collision energies are reached by measuring the reaction within the orbit of a Rydberg electron after merging a beam of He$(n)$ Rydberg atoms and a supersonic beam of CO molecules with a rotational temperature of $6.5 \, \textrm{K}$. The capture rate of the reaction drops by about $30\%$ at collision energies below $k_\textrm{B} \cdot 5~\textrm{K}$. This behavior is analyzed in terms of the long-range charge-dipole and charge-quadrupole interactions using an adiabatic-channel capture model. Although the charge-dipole interaction has an effect on the magnitude of the rate coefficients, the effects of the charge-quadrupole interaction determine the main trend of the collision-energy dependence of the rate coefficients at low collision energies. The drop of the capture rate coefficient at low collision energies is attributed to the negative sign of the quadrupole moment of CO ($Q_{zz} = -2.839 \, \textrm{D}$\AA) and is caused by the $|J|M|\rangle = |00\rangle$ and $|11\rangle$ rotational states of CO, which represent about $70\%$ of the CO molecules at the rotational temperature of $6.5 \, \textrm{K}$.

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“…We further assume that the rotational levels of p-H + 3 and o-H + 3 are each populated at formation according to their Boltzmann distribution at a temperature corresponding to 2/3 of the reaction exothermicity ( [30]). Given the low energy of the relevant levels, this amounts in effect at using rates proportional to the statistical weight of the level.…”

Section: Processes Controlling the Para Fraction Of Hmentioning

confidence: 99%

Understanding the temperatures of H3+ and H2 in diffuse interstellar sightlines

Bourlot¹,

Roueff²,

Petit³

et al. 2023

Preprint

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The triatomic hydrogen ion H + 3 is one of the most important species for the gas phase chemistry of the interstellar medium. Observations of H + 3 are used to constrain important physical and chemical parameters of interstellar environments. However, the temperatures inferred from the two lowest rotational states of H + 3 in diffuse lines of sight -typically the only ones observable -appear consistently lower than the temperatures derived from H2 observations in the same sightlines. All previous attempts at modeling the temperatures of H + 3 in the diffuse interstellar medium failed to reproduce the observational results.Here we present new studies, comparing an independent master equation for H + 3 level populations to results from the Meudon PDR code for photon dominated regions. We show that the populations of the lowest rotational states of H + 3 are strongly affected by the formation reaction and that H + 3 ions experience incomplete thermalization before their destruction by free electrons. Furthermore, we find that for quantitative analysis more than two levels of H + 3 have to be considered and that it is crucial to include radiative transitions as well as collisions with H2. Our models of typical diffuse interstellar sightlines show very good agreement with observational data, and thus they may finally resolve the perceived temperature difference attributed to these two fundamental species.

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Reactions of H₂, HD, and D₂ with H₂⁺, HD⁺, and D₂⁺: Product-Channel Branching Ratios and Simple Models

Abstract: We present measurements of the product-channel branching ratios of the reactions (i) HD + + HD forming H 2 D + + D (38.1(30)%) and HD 2 + + H (61.9(30)%), (ii) HD + + D 2 forming HD 2 + + D (61.4(35)%) and D 3 + + H (38.6(35)%), and (iii) D 2 + + HD formin… Show more

Cited by 11 publications

References 48 publications

Dissociative recombination and rotational transitions of D+2 in collisions with slow electrons

Dissociative recombination and rotational transitions of D+2 in collisions with slow electrons

Effects of the charge–dipole and charge–quadrupole interactions on the He⁺ + CO reaction rate coefficients at low collision energies

Understanding the temperatures of H3+ and H2 in diffuse interstellar sightlines

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Reactions of H2, HD, and D2 with H2+, HD+, and D2+: Product-Channel Branching Ratios and Simple Models

Abstract: We present measurements of the product-channel branching ratios of the reactions (i) HD + + HD forming H 2 D + + D (38.1(30)%) and HD 2 + + H (61.9(30)%), (ii) HD + + D 2 forming HD 2 + + D (61.4(35)%) and D 3 + + H (38.6(35)%), and (iii) D 2 + + HD formin… Show more

Cited by 11 publications

References 48 publications

Dissociative recombination and rotational transitions of D+2 in collisions with slow electrons

Dissociative recombination and rotational transitions of D+2 in collisions with slow electrons

Effects of the charge–dipole and charge–quadrupole interactions on the He+ + CO reaction rate coefficients at low collision energies

Understanding the temperatures of H3+ and H2 in diffuse interstellar sightlines

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Reactions of H₂, HD, and D₂ with H₂⁺, HD⁺, and D₂⁺: Product-Channel Branching Ratios and Simple Models

Effects of the charge–dipole and charge–quadrupole interactions on the He⁺ + CO reaction rate coefficients at low collision energies