Stabilization of H
            <sub>+</sub>
            –H
            <sub>2</sub>
            collision complexes between 11 and 28K

Plašil, R.; Zymak, Illia; Jusko, Pavol; Mulin, Dmytro; Gerlich, D.; Glosı́k, J.

doi:10.1098/rsta.2012.0098

Cited by 23 publications

(17 citation statements)

References 21 publications

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“…Moreover, at low temperatures, H 2 molecules also act as a buffer gas because of the low probability for a reactive collision. Recent experiments in our apparatus (Plašil et al 2012;Zymak et al 2013) as well as in other 22-pole trap experiments have confirmed that the collisional temperature is slightly higher than the temperature of the trap. In the present case we can safely assume that the collisional temperature in interaction of OD − with H 2 does not exceed the trap temperature by more than 10 K. For simplicity of presentation, we define the collisional temperature as T = T 22PT + 5 K with an uncertainty of ±5 K.…”

Section: Methodsmentioning

confidence: 72%

Effect of rotational excitation of H₂ on isotopic exchange reaction with OD⁻ at low temperatures

Roučka

Rednyk

Kovalenko

et al. 2018

A&A

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Aims. This paper presents experimentally obtained rate coefficients for the weakly endothermic reaction OD − + H 2 → OH − + HD with ortho-and para-hydrogen at astrophysically relevant temperatures between 10 and 300 K. Methods. The reaction was studied with normal and para-enriched (99.5% para-H 2 ) hydrogen in a 22-pole ion trap. The measured temperature dependencies of reaction rate coefficients are analyzed using a model which assumes that the rotational energies of the two reactants are equivalent to the translational energy in driving the reaction. Results. At room temperature, the rate coefficients of reactions with both nuclear spin variants reach 7 × 10 −11 cm 3 s −1 , which is in good agreement with the previous results from ion trap and swarm experiments with normal hydrogen. Cooling down the trap slows down the reaction and leads, at a nominal trap temperature of 11 K, to a rate coefficient below 10 −14 cm 3 s −1 for paraenriched hydrogen. The fitted reaction endothermicity of 25.3 ± 2.2 meV agrees well with the literature value calculated in the Born-Oppenheimer approximation, ∆H 0 = 24.0 meV. A simpler evaluation procedure, fitting the data with Arrhenius functions, results in p k = 16.8 × 10 −11 exp(−234 K/T ) cm 3 s −1 for pure para-hydrogen and o k = 9.4 × 10 −11 exp(−101 K/T ) cm 3 s −1 for pure orthohydrogen.

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Section: Methodsmentioning

confidence: 72%

Effect of rotational excitation of H₂ on isotopic exchange reaction with OD⁻ at low temperatures

Roučka

Rednyk

Kovalenko

et al. 2018

A&A

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“…14 The observed resonances observed here and for the scattering reactions for the H + 3 system 4 can be directly related with H + −H 2 radiative association processes. 44,60 In recent experimental radio frequency ion trap investigations, the deviations from the expected statistical behaviour were tentatively attributed to the rather low number of states accessible to the H + 3 complex at the temperature regime (11 K-33 K) considered there. In order to elucidate the issue more QM calculations on sufficiently precise PESs are required.…”

Section: Discussionmentioning

confidence: 99%

“…42,43 The apparent success of the statistical treatments for this system has been also questioned by recent experimental work in which binary rate coefficients were measured for the stabilization of H + −H 2 collision complexes by means of a radio frequency ion trap at a temperature between T = 11 K and 33 K. The observed behaviour of the rate coefficients for both j = 0 and j = 1 initial rotational states for H 2 manifested differences with respect to the expected results from models designed on statistical assumptions for the association to form and stabilize H + 3 complexes. 44 The above mentioned SQM approach was also employed for the D + +H 2 reaction on Ref. 45 besides TDWP calculations.…”

Section: Introductionmentioning

confidence: 99%

Dynamics of the D+ + H2 → HD + H+ reaction at the low energy regime by means of a statistical quantum method

González‐Lezana

Honvault

Scribano

2013

The Journal of Chemical Physics

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The D + +H 2 (v = 0, j = 0, 1) → HD+H + reaction has been investigated at the low energy regime by means of a statistical quantum mechanical (SQM) method. Reaction probabilities and integral cross sections (ICSs) between a collisional energy of 10 −4 eV and 0.1 eV have been calculated and compared with previously reported results of a time independent quantum mechanical (TIQM) approach. The TIQM results exhibit a dense profile with numerous narrow resonances down to E c ∼ 10 −2 eV and for the case of H 2 (v = 0, j = 0) a prominent peak is found at ∼2.5 × 10 −4 eV. The analysis at the state-to-state level reveals that this feature is originated in those processes which yield the formation of rotationally excited HD(v = 0, j > 0). The statistical predictions reproduce reasonably well the overall behaviour of the TIQM ICSs at the larger energy range (E c ≥ 10 −3 eV). Thermal rate constants are in qualitative agreement for the whole range of temperatures investigated in this work, 10-100 K, although the SQM values remain above the TIQM results for both initial H 2 rotational states, j = 0 and 1. The enlargement of the asymptotic region for the statistical approach is crucial for a proper description at low energies. In particular, we find that the SQM method leads to rate coefficients in terms of the energy in perfect agreement with previously reported measurements if the maximum distance at which the calculation is performed increases noticeably with respect to the value employed to reproduce the TIQM results. © 2013 AIP Publishing LLC.

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“…Energy scaling of TBR in charged gases was studied at temperatures down to a few K, especially for hydrogen and helium due to their relevance in plasmas and astrophysics (e.g. [5,6]). Depending on the studied temperature range a variety of power laws was found but not a common threshold law.…”

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confidence: 99%

Energy Scaling of Cold Atom-Atom-Ion Three-Body Recombination

et al. 2016

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We study three-body recombination of Ba + + Rb + Rb in the mK regime where a single 138 Ba + ion in a Paul trap is immersed into a cloud of ultracold 87 Rb atoms. We measure the energy dependence of the three-body rate coefficient k3 and compare the results to the theoretical prediction, k3 ∝ E −3/4 col where E col is the collision energy. We find agreement if we assume that the non-thermal ion energy distribution is determined by at least two different micro-motion induced energy scales. Furthermore, using classical trajectory calculations we predict how the median binding energy of the formed molecules scales with the collision energy. Our studies give new insights into the kinetics of an ion immersed into an ultracold atom cloud and yield important prospects for atom-ion experiments targeting the s-wave regime.When three atoms collide, a diatomic molecule can form in a three-body recombination (TBR) process. In cold neutral atomic gases, TBR was investigated for spinpolarized hydrogen as well as alkalis (see e.g. [1][2][3]). In the context of Bose-Einstein condensation, TBR plays a crucial role as a main loss mechanism. By now, the scaling of TBR as a function of collision energy and scattering lengths in neutral ultracold gases has been investigated in detail [4]. When considering TBR in atom-ion systems, one can expect three-body interactions to be more pronounced due to the underlying longer-range r −4 polarization potential. Energy scaling of TBR in charged gases was studied at temperatures down to a few K, especially for hydrogen and helium due to their relevance in plasmas and astrophysics (e.g. [5,6]). Depending on the studied temperature range a variety of power laws was found but not a common threshold law. The recent development of novel hybrid traps for both laser cooled atoms and ions has opened the possibility to investigate cold atom-ion interactions and chemical reactions in the mK-regime and below. First experiments in such setups studied elastic and reactive two-body collisions (e.g. [7][8][9][10][11][12][13][14]). In accordance with the well-known Langevin theory, the corresponding reactive rates were measured to be independent of the collision energy [8,10]. Very recently we predicted a theoretical threshold law on the scaling properties for cold atom-atom-ion three-body collisions [15]. Understanding the scaling of reaction rates with quantities such as the collision energy is crucial for fundamentally understanding TBR and for the prospects of the experimental realization of ultracold s-wave atom-ion collisions. Furthermore, as we will show here, studying TBR allows for insights into the kinetics of an ion immersed in a cloud of atoms. This letter reports on the combined theoretical and experimental investigation of the energy scaling of threebody atom-atom-ion collisions in the mK regime. We measure the TBR rate coefficient k 3 of Ba + in an ultracold Rb cloud as a function of the mean collision energy of the ion, E col , which we control via the excess micromotion (eMM) of the Paul trap...

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Stabilization of H ₊ –H ₂ collision complexes between 11 and 28K

Abstract: Formation of via association of H + with H 2 has been studied at low temperatures using a 22-pole radiofrequency trap. Operating at hydrogen number densities from 10 11 to 10 14 cm −3 , the contributions of radiative, k r , and ternary, k 3 , association have been extr… Show more

Cited by 23 publications

References 21 publications

Effect of rotational excitation of H₂ on isotopic exchange reaction with OD⁻ at low temperatures

Effect of rotational excitation of H₂ on isotopic exchange reaction with OD⁻ at low temperatures

Dynamics of the D+ + H2 → HD + H+ reaction at the low energy regime by means of a statistical quantum method

Energy Scaling of Cold Atom-Atom-Ion Three-Body Recombination

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Stabilization of H + –H 2 collision complexes between 11 and 28K

Abstract: Formation of via association of H + with H 2 has been studied at low temperatures using a 22-pole radiofrequency trap. Operating at hydrogen number densities from 10 11 to 10 14 cm −3 , the contributions of radiative, k r , and ternary, k 3 , association have been extr… Show more

Cited by 23 publications

References 21 publications

Effect of rotational excitation of H2 on isotopic exchange reaction with OD− at low temperatures

Effect of rotational excitation of H2 on isotopic exchange reaction with OD− at low temperatures

Dynamics of the D+ + H2 → HD + H+ reaction at the low energy regime by means of a statistical quantum method

Energy Scaling of Cold Atom-Atom-Ion Three-Body Recombination

Contact Info

Product

Resources

About

Stabilization of H ₊ –H ₂ collision complexes between 11 and 28K

Effect of rotational excitation of H₂ on isotopic exchange reaction with OD⁻ at low temperatures

Effect of rotational excitation of H₂ on isotopic exchange reaction with OD⁻ at low temperatures