Hydrogen recombination due to collisions with He and Ar

Paolini, Stephen; Ohlinger, Luke; Forrey, Robert C.

doi:10.1103/physreva.83.042713

Cited by 6 publications

(14 citation statements)

References 31 publications

(60 reference statements)

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“…As a consequence, the agreement with approximate quantum method estimates reported in Ref. [44] is much better, as shown in Fig. (6), where the two results differ mainly in the temperature region around 10000 K for at most a factor two.…”

Section: Atom-diatom Systemssupporting

confidence: 66%

“…On that ground by considering the discretization of the continuum (as well as the coupled states approximation used in Ref. [44]) and taking into account the high initial vibrational level considered, it would be not surprising to find that quasi-classical results reproduce the (not yet available) experimental data. However, it is interesting to note that, at least for this system, quasi-classical rotovibrational energy transfer results clearly fail to provide an adequate final analysis of product properties at low translational energy (<0.1 eV), while they well reproduce quantum mechanical dissociation in the same range.…”

Section: Atom-diatom Systemsmentioning

confidence: 88%

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Molecular Physics of Elementary Processes Relevant to Hypersonics: Atom-Molecule, Molecule-Molecule and Atoms-Surface Processes

Laganá¹,

Lombardi²,

Pirani³

et al. 2014

TOPPJ

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Abstract:In the present chapter some prototype gas and gas-surface processes occurring within the hypersonic flow layer surrounding spacecrafts at planetary entry are discussed. The discussion is based on microscopic dynamical calculations of the detailed cross sections and rate coefficients performed using classical mechanics treatments for atoms, molecules and surfaces. Such treatment allows the evaluation of the efficiency of thermal processes (both at equilibrium and non equilibrium distributions) based on state-to-state and state specific calculations properly averaged over the population of the initial states. The dependence of the efficiency of the considered processes on the initial partitioning of energy among the various degrees of freedom is discussed.

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Section: Atom-diatom Systemssupporting

confidence: 66%

Section: Atom-diatom Systemsmentioning

confidence: 88%

Molecular Physics of Elementary Processes Relevant to Hypersonics: Atom-Molecule, Molecule-Molecule and Atoms-Surface Processes

Laganá¹,

Lombardi²,

Pirani³

et al. 2014

TOPPJ

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“…As was noted previously [5], there is significant uncertainty in the MR PES when the H-H bond is stretched. This uncertainty can have an affect on the TBR rate constant and is the most likely source of the discrepancy between the CS results and the experiment.…”

Section: Resultsmentioning

confidence: 55%

“…This approach was used by Paolini, Ohlinger, and Forrey [5] to compute TBR rates for H 2 due to collisions with He and Ar. The results appeared promising and confirmed the importance of non-resonant contributions to recombination observed in earlier works [6,7].…”

Section: Introductionmentioning

confidence: 99%

Sturmian theory of three-body recombination: Application to the formation of H2in primordial gas

Forrey

2013

Phys. Rev. A

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A Sturmian theory of three-body recombination is presented which provides a unified treatment of bound states, quasi-bound states, and continuum states.The Sturmian representation provides a numerical quadrature of the two-body continuum which may be used to generate a complete set of states within any desired three-body recombination pathway. Consequently, the dynamical calculation may be conveniently formulated using the simplest energy transfer mechanism, even for reactive systems which allow substantial rearrangement.The Sturmian theory generalizes the quantum kinetic theory of Snider and Lowry [J. Chem. Phys. 61, 2330(1974] to include metastable states which are formed as independent species. Steady-state rate constants are expressed in terms of a pathway-independent part plus a non-equilibrium correction which depends on tunneling lifetimes and pressure. Numerical results are presented for H 2 recombination due to collisions with H and He using quantum mechanical coupled states and infinite order sudden approximations. These results may be used to remove some of the uncertainties that have limited astrophysical simulations of primordial star formation.

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“…The energy E i is a positive energy eigenvalue of the diatomic Schrödinger equation in a Sturmian basis set representation, which may correspond to a resonance or to a discretized non-resonant contribution in a numerical quadrature of the continuum 86 . We use a Sturmian basis set representation consisting of 100 Laguerre polynomial L (2l+2) n functions of the form φ l,n (r) = a s n!…”

Section: Molecular Formationmentioning

confidence: 99%

Formation and dynamics of van der Waals molecules in buffer-gas traps

Brahms

Tscherbul

Zhang

et al. 2011

Phys. Chem. Chem. Phys.

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We show that weakly bound He-containing van der Waals molecules can be produced and magnetically trapped in buffer-gas cooling experiments, and provide a general model for the formation and dynamics of these molecules. Our analysis shows that, at typical experimental parameters, thermodynamics favors the formation of van der Waals complexes composed of a helium atom bound to most open-shell atoms and molecules, and that complex formation occurs quickly enough to ensure chemical equilibrium. For molecular pairs composed of a He atom and an S-state atom, the molecular spin is stable during formation, dissociation, and collisions, and thus these molecules can be magnetically trapped. Collisional spin relaxations are too slow to affect trap lifetimes. However, 3 He-containing complexes can change spin due to adiabatic crossings between trapped and untrapped Zeeman states, mediated by the anisotropic hyperfine interaction, causing trap loss. We provide a detailed model for Ag 3 He molecules, using ab initio calculation of Ag-He interaction potentials and spin interactions, quantum scattering theory, and direct Monte Carlo simulations to describe formation and spin relaxation in this system. The calculated rate of spin-change agrees quantitatively with experimental observations, providing indirect evidence for molecular formation in buffer-gas-cooled magnetic traps.The ability to cool and trap molecules holds great promise for new discoveries in chemistry and physics [1][2][3][4] . Cooled and trapped molecules yield long interaction times, allowing for precision measurements of molecular structure and interactions, tests of fundamental physics 5,6 , and applications in quantum information science 7 . Chemistry shows fundamentally different behavior for cold molecules 8 , and can be highly controlled based on the kinetic energy, external fields 9 , and quantum states 10 of the reactants.Experiments with cold molecules have thus far involved two classes of molecules: Feshbach molecules and deeply bound ground-state molecules. Feshbach molecules are highly vibrationally excited molecules, bound near dissociation, which interact only weakly at long range, due to small dipole moments. They are created by binding pairs of ultracold atoms using laser light (photoassociation), ac magnetic fields (rf as- . By contrast, ground-state heteronuclear molecules often have substantial dipole moments and are immune to spontaneous decay and vibrational relaxation, making these molecules more promising for applications in quantum information processing 7 and quantum simulation 11 . These molecules are either cooled from high temperatures using techniques such as buffer-gas cooling or Stark deceleration, or are created via coherent deexcitation of Feshbach molecules.This article introduces a third family to the hierarchy of trappable molecules -van der Waals (vdW) complexes. VdW molecules are bound solely by long-range dispersion interactions, leading to the weakest binding energies of any groundstate molecules, on the order of a wavenum...

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Hydrogen recombination due to collisions with He and Ar

Cited by 6 publications

References 31 publications

Molecular Physics of Elementary Processes Relevant to Hypersonics: Atom-Molecule, Molecule-Molecule and Atoms-Surface Processes

Molecular Physics of Elementary Processes Relevant to Hypersonics: Atom-Molecule, Molecule-Molecule and Atoms-Surface Processes

Sturmian theory of three-body recombination: Application to the formation of H2in primordial gas

Formation and dynamics of van der Waals molecules in buffer-gas traps

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