Association reactions with state selected ions at meV collision energies: CO+ (v=0,j) + 2 CO → (CO)+2+CO

Gerlich, D.; Rox, T.

doi:10.1007/bf01436963

Cited by 23 publications

(10 citation statements)

References 22 publications

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“…We also note that for fast exothermic reactions (without barriers), the internal excitation of a reactant can actually inhibit the reactivity, as observed experimentally for ion-molecule (e.g Gerlich & Rox 1989(Olkhov & Smith 2007) reactions.…”

supporting

confidence: 58%

THE CHEMISTRY OF VIBRATIONALLY EXCITED H₂IN THE INTERSTELLAR MEDIUM

Agúndez

Goicoechea

Cernicharo

et al. 2010

ApJ

150

186

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The internal energy available in vibrationally excited H 2 molecules can be used to overcome or diminish the activation barrier of various chemical reactions of interest for molecular astrophysics. In this article we investigate in detail the impact on the chemical composition of interstellar clouds of the reactions of vibrationally excited H 2 with C + , He + , O, OH, and CN, based on the available chemical kinetics data. It is found that the reaction of H 2 (v > 0) and C + has a profound impact on the abundances of some molecules, especially CH + , which is a direct product and is readily formed in astronomical regions with fractional abundances of vibrationally excited H 2 , relative to ground state H 2 , in excess of ∼ 10 −6 , independently of whether the gas is hot or not. The effects of these reactions on the chemical composition of the diffuse clouds ζ Oph and HD 34078, the dense PDR Orion Bar, the planetary nebula NGC 7027, and the circumstellar disk around the B9 star HD 176386 are investigated through PDR models. We find that formation of CH + is especially favored in dense and highly FUV illuminated regions such as the Orion Bar and the planetary nebula NGC 7027, where column densities in excess of 10 13 cm −2 are predicted. In diffuse clouds, however, this mechanism is found to be not efficient enough to form CH + with a column density close to the values derived from astronomical observations.

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confidence: 58%

THE CHEMISTRY OF VIBRATIONALLY EXCITED H₂IN THE INTERSTELLAR MEDIUM

Agúndez

Goicoechea

Cernicharo

et al. 2010

ApJ

150

186

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“…For example, this photoionization for molecular ion creation were done approach was used in the study of the dependence of ternary by Anderson et a1.,i4 in which the propensity rules for association rate constants on the rotational state of Cot. In order to obtain an observable association rate (with CO as the vibrational autoionization were exploited to generate third body) the ions were generated in the expansion, about 6 nozzle diameters downstream. In this region the number denvibrationally selected primary ions.…”

Section: Single Beam Experiments Vs Merged and Crossed Beam Setupsmentioning

confidence: 99%

Single and Merged Beam Studies of the Reaction H₂⁺ (v = 0,1; j = 0,4) + H₂ → H₃⁺ + H

Glenewinkel-Meyer

Gerlich

1997

Israel Journal of Chemistry

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Abstract. Different approaches for studying low-energy (mev) reactive ionmolecule collisions in molecular beams are presented. In particular, differences in the photoionization (REsonant Multi-Photon Ionization / REMPI, Pulsed Field Ionization / PFI) experiments using single molecular beams vs. merged and crossed beams are discussed. We address the question of the proper determination of cross sections and rate constants in single beam experiments and the factors that influence the width of the collision energy distributions. We identify space charge effects as the dominant contribution under our experimental conditions. Problems pertinent to state-selected primary ion preparation with narrow energy distributions are highlighted.In light of the detailed data analysis, the derived relations are applied to the fourcenter reaction + H2 + H,+ + H, which was studied in single and merged molecular beam experiments. We present merged beam data for the absolute reaction cross section for primary ions created in a storage ion source in the energy range from 5 meV up to 5 eV and relative state-selected cross sections for different vibrational and rotational ion states (v = 0,l; j = 0-4) generated by (3+1) REMPI for a mean collision energy of about 10 meV. INTRODUCTION Ion-molecule reactions at meV collision energies play an important role in the energy and particle balance of the interstellar medium. Even though it is very complicated to model interstellar conditions in the laboratory, various experimental approaches for studying ion-molecule reactions at these low energies have been made to date. The apparatuses for these studies comprise mostly single molecular beam or flow system setups, but recently very sensitive and more general devices such as cooled ion traps, ion storage, and merged beam devices have been used.Early setups, like DRIFT and @-He cooled SIFT tubes,' utilize a uniform flow of ions embedded in a buffer gas through a tube in which reactants are injected at different positions of the flow. Reaction rates can then be deduced from the target density dependence of the product signal at the detector. The length of the reaction region is essentially given by the distance between injection and detection.In order to achieve smaller collision energies or lower temperatures of the buffer gas in which the collisions take place, beam expansions have been employed.

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“…Prominent exceptions are the charge transfer reactions of atomic cations with diatomics exhibiting high frequency vibrational mode, e.g. 7 For H-abstraction by NO + from ethanol 8 and for charge transfer from N 2 + to Ar 9 no discernible effect of the external rotation on the cross section has been observed. E.g., for the charge transfer reaction Kr + + HCl -Kr + HCl + , the cross section decreases with increasing rotational temperature of the neutral HCl.…”

Section: Introductionmentioning

confidence: 99%

Self-reactions in the HCl⁺ (DCl⁺) + HCl system: a state-selective investigation of the role of rotation

Uhlemann

Wallauer

Weitzel

2015

Phys. Chem. Chem. Phys.

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The self-reaction of state-selected HCl(+) (DCl(+)) ions with HCl has been investigated in a guided ion beam setup. The absolute cross sections for proton transfer and deuteron transfer decrease with increasing center of mass collision energy, Ec.m.. The cross section for charge transfer (DCl(+) + HCl) exhibits a maximum at Ec.m. = 0.5 eV. The cross section for PT and DT decrease significantly with increasing rotational angular momentum in the molecular ion, for the PT the cross section increases again for the highest angular momentum investigated. The rotational dependence of the cross section is rationalized by a simple model in which both the collision energy and part of the rotational energy are available for the reaction. The contribution of the rotation to the total energy available itself depends on the collision energy.

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Association reactions with state selected ions at meV collision energies: CO+ (v=0,j) + 2 CO → (CO)+2+CO

Cited by 23 publications

References 22 publications

THE CHEMISTRY OF VIBRATIONALLY EXCITED H₂IN THE INTERSTELLAR MEDIUM

THE CHEMISTRY OF VIBRATIONALLY EXCITED H₂IN THE INTERSTELLAR MEDIUM

Single and Merged Beam Studies of the Reaction H₂⁺ (v = 0,1; j = 0,4) + H₂ → H₃⁺ + H

Self-reactions in the HCl⁺ (DCl⁺) + HCl system: a state-selective investigation of the role of rotation

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Association reactions with state selected ions at meV collision energies: CO+ (v=0,j) + 2 CO → (CO)+2+CO

Cited by 23 publications

References 22 publications

THE CHEMISTRY OF VIBRATIONALLY EXCITED H2IN THE INTERSTELLAR MEDIUM

THE CHEMISTRY OF VIBRATIONALLY EXCITED H2IN THE INTERSTELLAR MEDIUM

Single and Merged Beam Studies of the Reaction H2+ (v = 0,1; j = 0,4) + H2 → H3+ + H

Self-reactions in the HCl+ (DCl+) + HCl system: a state-selective investigation of the role of rotation

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THE CHEMISTRY OF VIBRATIONALLY EXCITED H₂IN THE INTERSTELLAR MEDIUM

THE CHEMISTRY OF VIBRATIONALLY EXCITED H₂IN THE INTERSTELLAR MEDIUM

Single and Merged Beam Studies of the Reaction H₂⁺ (v = 0,1; j = 0,4) + H₂ → H₃⁺ + H

Self-reactions in the HCl⁺ (DCl⁺) + HCl system: a state-selective investigation of the role of rotation