| 1. |
- Bogot, Alon, et al.
(author)
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The mutual neutralization of hydronium and hydroxide
- 2024
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In: Science. - 0036-8075 .- 1095-9203. ; 383:6680, s. 285-289
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Journal article (peer-reviewed)abstract
- Mutual neutralization of hydronium (H3O+) and hydroxide (OH−) ions is a very fundamental chemical reaction. Yet, there is only limited experimental evidence about the underlying reaction mechanisms. Here, we report three-dimensional imaging of coincident neutral products of mutual-neutralization reactions at low collision energies of cold and isolated ions in the cryogenic double electrostatic ion-beam storage ring (DESIREE). We identified predominant H2O + OH + H and 2OH + H2 product channels and attributed them to an electron-transfer mechanism, whereas a minor contribution of H2O + H2O with high internal excitation was attributed to proton transfer. The reported mechanism-resolved internal product excitation, as well as collision-energy and initial ion-temperature dependence, provide a benchmark for modeling charge-transfer mechanisms.
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| 2. |
- Dochain, Arnaud, 1989-, et al.
(author)
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Isotope effect for the mutual neutralization reaction at low collision energies : He++H−
- 2023
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In: Physical Review A: covering atomic, molecular, and optical physics and quantum information. - 2469-9926 .- 2469-9934. ; 108:4
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Journal article (peer-reviewed)abstract
- We measured the branching ratios of the He+ + H- and He+ + D- mutual neutralization at a collision energy below 25 meV. Those are correctly reproduced using the Landau-Zener model applied to potential energy curves computed by an anion-centered asymptotic model. The analyticity of both models allows getting a deeper insight into the reaction. It allows defining a low collision energy regime for the mutual neutralization at which the collision energy no longer affects the branching ratios. Using those models, we explain how heavier isotopes favor the production of higher excited states.
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| 3. |
- Dochain, Arnaud, 1989-, et al.
(author)
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Search for entanglement in the decay dynamics and anisotropic emission of a pair of H(2p) atoms produced by XUV photodissociation of H2
- 2023
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In: Physical Review A: covering atomic, molecular, and optical physics and quantum information. - 2469-9926 .- 2469-9934. ; 107:1
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Journal article (peer-reviewed)abstract
- The production of pairs of correlated Lyman-alpha photons upon XUV excitation of molecular hydrogen is studied using coincidence measurements to evaluate at which level the entanglement is transferred from atoms to photons. By referencing the timing of fluorescence photon detection to the synchrotron light pulse, we were able to determine branching ratios for the 2p + 2p and 2p + 3 (with = s, d) channels separately. Time-dependent analysis of the spectral signature recorded around 33.6 eV and close examination of the doubly excited states lying in the Franck-Condon window confirm prior assignments of the 2p + 2p being the main dissociation channel of the Q2 1 pi u (1) molecular state. The angular dependence of the two-photon detection probability measured with respect to the polarization axis is found to be in agreement with earlier measurements [Y. Torizuka et al., Phys. Rev. A 99, 063426 (2019)]. A simple model, assuming a transition from Hund's case (a) to Hund's case (c), reproduces the measured angular distributions satisfactorily.
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| 4. |
- Schmidt-May, Alice F., 1988-, et al.
(author)
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State-resolved mutual neutralization of 16O+ with 1H− and 2H− at collision energies below 100 meV
- 2024
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In: Physical Review A: covering atomic, molecular, and optical physics and quantum information. - : American Physical Society. - 2469-9926 .- 2469-9934. ; 109:5
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Journal article (peer-reviewed)abstract
- We measured the product-state distribution and its dependence on the hydrogen isotope for the mutual neutralization between 16O+ and 1,2H− at the double electrostatic ion-beam storage ring DESIREE for center-of-mass collision energies below 100 meV. We find at least six product channels into ground-state hydrogen and oxygen in different excited states. The majority of oxygen products populate terms corresponding to 2?22?3(4?∘)4? with 5S∘ as the main reaction product. We also observe product channels into terms corresponding to 2?22?3(4?)3?. Collisions with the heavier hydrogen isotope yield a branching into these lower excited states smaller than collisions with 1H−. The observed reaction products agree with the theoretical predictions. The detailed branching fractions, however, differ between the theoretical results, and none of them fully agree with the experiment.
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