Dynamics of Dissociative Recombination of Molecular Ions:  Three-Body Breakup of Triatomic Di-Hydrides†

2001 ◽  
Vol 105 (11) ◽  
pp. 2369-2373 ◽  
Author(s):  
Sheldon Datz
Keyword(s):  
Dissociative Recombination ◽  
Molecular Ions ◽  
Three Body

Dissociative recombination of electrons and molecular ions

1982 ◽  
Vol 136 (1) ◽  
pp. 25 ◽  
Author(s):  
Aleksandr V. Eletskii ◽  
Boris M. Smirnov
Keyword(s):  
Dissociative Recombination ◽  
Molecular Ions

scholarly journals Inferring thermospheric composition from ionogram profiles: a calibration with the TIMED spacecraft

2021 ◽  
Vol 39 (2) ◽  
pp. 309-319
Author(s):  
Christopher J. Scott ◽  
Shannon Jones ◽  
Luke A. Barnard
Keyword(s):  
Dissociative Recombination ◽  
Molecular Ions ◽  
Upper Atmosphere ◽  
Global Network ◽  
G Factor ◽  
Important Region ◽  
Term Change ◽  
Ion Production ◽  
Sensitive Function

Abstract. We present a method for augmenting spacecraft measurements of thermospheric composition with quantitative estimates of daytime thermospheric composition below 200 km, inferred from ionospheric data, for which there is a global network of ground-based stations. Measurements of thermospheric composition via ground-based instrumentation are challenging to make, and so details about this important region of the upper atmosphere are currently sparse. The visibility of the F1 peak in ionospheric soundings from ground-based instrumentation is a sensitive function of thermospheric composition. The ionospheric profile in the transition region between F1 and F2 peaks can be expressed by the “G” factor, a function of ion production rate and loss rates via ion–atom interchange reactions and dissociative recombination of molecular ions. This in turn can be expressed as the square of the ratio of ions lost via these processes. We compare estimates of the G factor obtained from ionograms recorded at Kwajalein (9∘ N, 167.2∘ E) for 25 times during which the Thermosphere, Ionosphere, Mesosphere, Energetics and Dynamics (TIMED) spacecraft recorded approximately co-located measurements of the neutral thermosphere. We find a linear relationship between G and the molecular-to-atomic composition ratio, with a gradient of 2.55±0.40. Alternatively, using hmF1 values obtained by ionogram inversion, this gradient was found to be 4.75±0.4. Further, accounting for equal ionisation in molecular and atomic species yielded a gradient of 4.20±0.8. This relationship has potential for using ground-based ionospheric measurements to infer quantitative variations in the composition of the neutral thermosphere via a relatively simple model. This has applications in understanding long-term change and the efficacy of the upper atmosphere on satellite drag.

scholarly journals Quantum-state–selective electron recombination studies suggest enhanced abundance of primordial HeH+

Science ◽  
2019 ◽  
Vol 365 (6454) ◽  
pp. 676-679 ◽  
Author(s):  
Oldřich Novotný ◽  
Patrick Wilhelm ◽  
Daniel Paul ◽  
Ábel Kálosi ◽  
Sunny Saurabh ◽  
...  
Keyword(s):  
Galaxy Formation ◽  
Dissociative Recombination ◽  
Molecular Ions ◽  
Rate Coefficients ◽  
Specific Rate ◽  
Electron Recombination ◽  
Recombination Rates ◽  
Rotational States ◽  
Hydride Ion ◽  
Helium Hydride

The epoch of first star formation in the early Universe was dominated by simple atomic and molecular species consisting mainly of two elements: hydrogen and helium. Gaining insight into this constitutive era requires a thorough understanding of molecular reactivity under primordial conditions. We used a cryogenic ion storage ring combined with a merged electron beam to measure state-specific rate coefficients of dissociative recombination, a process by which electrons destroy molecular ions. We found a pronounced decrease of the electron recombination rates for the lowest rotational states of the helium hydride ion (HeH+), compared with previous measurements at room temperature. The reduced destruction of cold HeH+ translates into an enhanced abundance of this primordial molecule at redshifts of first star and galaxy formation.

The dissociative recombination of cold polyatomic molecular ions measured at a storage ring

1997 ◽  
Author(s):  
O. Heber ◽  
L. H. Andersen ◽  
D. Kella ◽  
H. B. Pedersen ◽  
L. Vejby-Christensen ◽  
...  
Keyword(s):  
Storage Ring ◽  
Dissociative Recombination ◽  
Molecular Ions

scholarly journals Inferring thermospheric composition from ionogram profiles: A calibration with the TIMED spacecraft

2019 ◽  
Author(s):  
Christopher J. Scott ◽  
Shannon Jones ◽  
Luke A. Barnard
Keyword(s):  
Dissociative Recombination ◽  
Temporal Variations ◽  
Molecular Ions ◽  
Upper Atmosphere ◽  
Global Network ◽  
G Factor ◽  
Satellite Drag ◽  
Important Region ◽  
Ion Production ◽  
Sensitive Function

Abstract. Measurements of thermospheric composition via ground-based instrumentation are challenging to make and so details about this important region of the upper atmosphere are currently sparse. We present a technique that deduces quantitative estimates of thermospheric composition from ionospheric data, for which there is a global network of stations. The visibility of the F1 peak in ionospheric soundings from ground-based instrumentation is a sensitive function of thermospheric composition. The ionospheric profile in the transition region between F1 and F2 peaks can be expressed by the G factor, a function of ion production rate and loss rates via ion-atom interchange reactions and dissociative recombination of molecular ions. This in turn can be expressed as the square of the ratio of ions lost via these processes. We compare estimates of the G factor obtained from ionograms recorded at Kwajalein (9° N, 167.2° E) for 25 times during which the TIMED spacecraft recorded approximately co-located measurements of the neutral thermosphere. We find a linear relationship between √G and the molecular: atomic composition ratio, with a gradient of 2.23 ± 0.17 and an offset of 1.66 ± 0.19. This relationship reveals the potential for using ground-based ionospheric measurements to infer quantitative variations in the composition of the neutral thermosphere. Such information can be used to investigate spatial and temporal variations in thermospheric composition which in turn has applications such as understanding the response of thermospheric composition to climate change and the efficacy of the upper atmosphere on satellite drag.

scholarly journals Dissociative recombination of stored and phase-spaced cooled molecular ions in cryring

1993 ◽  
Author(s):  
M. Larsson ◽  
G. Sundström ◽  
M. Carlson ◽  
H. Danared ◽  
A. Källberg ◽  
...  
Keyword(s):  
Dissociative Recombination ◽  
Molecular Ions

Ionization of alkaline earth additives in hydrogen flames - I. Hydrogen atom concentrations and ion stabilities

1974 ◽  
Vol 338 (1613) ◽  
pp. 155-173 ◽  
Keyword(s):  
Alkaline Earth ◽  
Molecular Ions ◽  
The Other ◽  
Hydrogen Atoms ◽  
Ion Hydration ◽  
Atomic Ions ◽  
Charged Species ◽  
Hydration Energies ◽  
Three Body ◽  
Species Being

The ions present in flames of H 2 +O 2 + N 2 with trace quantities of an alkaline earth M ( = Ca or Sr) added to them have been studied mass spectrometrieally. Those detected were principally MOH + and M + , the only negatively charged species being the free electron. It was established that the reaction M + +H 2 O = MOH + +H was rapid enough to be balanced everywhere in a flame. Detailed studies of (I) provided a means for measuring the concentration of hydrogen atoms at the point of sampling in the flame from observations of [M + ]/[MOH + ]. It proved possible to make absolute determinations of [H]. In addition, the ionization potentials of CaOH and SrOH were measured as 5.7 ± 0.3 and 5.4 ± 0.3 eV, which values are slightly less than those for the corresponding alkaline earth atoms. Hydrates of MOH + and M + were observed, but it was concluded that ion-hydration is not an important flame process in this case, but rather one associated with cooling of gases as they are sampled into the mass spectrometer. It appears that molecular ions hydrate in a two-body process, e. g. MOH + + H 2 O → MOH + . H 2 O with a velocity constant, which is independent of temperature and approximately 1 x 10 –10 ml molecule –1 s –1 . Atomic ions on the other hand initially undergo hydration by a slower three-body step requiring a chaperon molecule. The first hydration energies at absolute zero for CaOH + and SrOH + were measured to be 120±20 and 109±15 kJ mol –1 respectively. These exceed the corresponding quantities for Ca + and Sr + , which were found to be 75±16 and 60±16 kJ mol –1 .

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