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Fedchak, J. A.; Huels, Michael A.; Doverspike, L. D.; Champion, R. L.

doi:10.1103/physreva.47.3796

Cited by 13 publications

(3 citation statements)

References 16 publications

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“…A reaction that possibly could compete with the radiative association processes is electron detachment, and A method to approximate an upper limit to the cross-section of electron detachment can be found in an experimental study on O – + H . In this approximation it is assumed that in all cases when the classical trajectory reaches a point in space where the potential energy surface of the reactants cross the potential energy surface of the ground state of the products, the reaction occurs.…”

Section: Theoretical Methodsmentioning

confidence: 99%

Formation of the Hydroxyl Radical by Radiative Association

2015

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The reaction rate constant for the radiative association of O((3)P) and H((2)S) has been calculated by combining a few different methods and taking account of both direct and resonance-mediated pathways. The latter includes both shape resonances and Feshbach type inverse predissociation. The reaction rate constant is expressed as a function of temperature in the interval 10-30000 K. This reaction may be astrochemically relevant and is expected to be of use in astrochemical networks.

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Section: Theoretical Methodsmentioning

confidence: 99%

Formation of the Hydroxyl Radical by Radiative Association

2015

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“…For reaction 3.h an upper bound to the reaction cross section was estimated through a method that has been used for O − + H. 80 This approximate method assumes that, for a certain electronic state all classical trajectories that reach the point where the potential energy surface of this electronic state crosses the potential energy surface of the electronic state with a detached electron, x cross , leads to a reaction,…”

Section: Electron Detachmentmentioning

confidence: 99%

Classical Wigner model based on a Feynman path integral open polymer

Svensson

Poulsen

Nyman

2020

The Journal of Chemical Physics

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When using mathematical models to computationally investigate a chemical system it is important that the methods used are accurate enough to account for the relevant properties of the system and at the same time simple enough to be computationally affordable. This thesis presents research that so far has resulted in three published papers and one unpublished manuscript. It concerns the application and development of computational methods for chemistry, with some extra emphasis on the calculation of reaction rate constants. In astrochemistry radiative association is a relevant reaction mechanism for the formation of molecules. The rate constants for such reactions are often difficult to obtain though experiments. In the first published paper of the thesis a rate constant for the formation of the hydroxyl radical, through the radiative association of atomic oxygen and hydrogen, is presented. This rate constant was calculated by a combination of different methods and should be an improvement over previously available rate constants. In the the second published paper of this thesis two kinds of basis functions, for use with a variational principle for the dynamics of quantum distributions in phase space, i.e. Wigner functions, is presented. These are tested on model systems and found to have some appealing properties. The classical Wigner method is an approximate method of simulation, where an initial quantum distribution is propagated in time with classical mechanics. In the third published paper of this thesis a new method of sampling the initial quantum distribution, with an imaginary time Feynman path integral, is derived and tested on model systems. In the unpublished manuscript, this new method is applied to reaction rate constants and tested on two model sysv Abstract tems. The new sampling method shows some promise for future applications. vi Preface You have guessed right; I have lately been so deeply engaged in one occupation that I have not allowed myself sufficient rest, as you see: but I hope, I sincerely hope, that all these employments are now at an end, and that I am at length free.

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“…To date no electron energy spectra for AD processes in collisions of atomic negative ions with atoms (in particular Y = H) have been reported to our knowledge. Some experimental data do exist for the collision energy dependence of the total AD cross section in reactions of atomic hydrogen [6] and halogen anions [7] with hydrogen atoms and for some other simple diatomic systems [8,9]. Total cross sections, however, do not represent a sensitive probe of the theoretical description, and it is therefore highly desirable to elucidate the detailed consequences of different facets of the theory through predictions of experimentally observable differences in the partial (v, J ) cross sections σ vJ (E), as detectable in electron energy spectra or-as in the case of the hydrogen halides-via infrared spectroscopy [10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Associative detachment in low-energy collisions between hydrogen atoms and atomic halogen anions

Čı́žek

Horáček

Thiel

et al. 2001

J. Phys. B: At. Mol. Opt. Phys.

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Using an improved nonlocal resonance theory, total cross sections, rovibrational final state distributions and electron spectra for low-energy (<2 eV) associative detachment (AD) collisions between hydrogen atoms and negative halogen ions X- (X = F, Cl, Br) as well as deuterium atoms and F- ions have been calculated. The model involves realistic long-range interactions for the H + X- systems and takes into account the dependence of the dipole-modified threshold exponent on internuclear distance. Good agreement is found between experimental data for the total AD cross sections and the theoretical results. In the calculated electron energy spectra nonlocal effects are manifest through step structure which is (almost) independent of collision energy; this structure should therefore be observable in experiments with rather modest collision energy resolution. For illustration, electron spectra are presented which correspond to realistic experimental conditions with regard to the energy widths of the electron spectrometer and the collision energy distribution. The rovibrational final-state distributions in the HX(v, J) molecules formed are reported for a thermal kinetic energy distribution at T ≈ 300 K; for HF, DF and HCl the rotational-summed vibrational populations pv are compared with previous theoretical and experimental results.

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Electron detachment and charge transfer for collisions ofO−andS−<

Cited by 13 publications

References 16 publications

Formation of the Hydroxyl Radical by Radiative Association

Formation of the Hydroxyl Radical by Radiative Association

Classical Wigner model based on a Feynman path integral open polymer

Associative detachment in low-energy collisions between hydrogen atoms and atomic halogen anions

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