Dissociative recombination of rare gas hydride ions: II. ArH<sup>+</sup>

Mitchell, James B.; Novotny, Steffen; LeGarrec, J L; Florescu-Mitchell, A. I.; Rebrion-Rowe, C.; Stolyarov, A. V.; Child, M. S.; Svendsen, Annette; Ghazaly, M A El; Andersen, L. H.

doi:10.1088/0953-4075/38/10/l07

Cited by 38 publications

(33 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The rate coefficient used for the ArH + + e − reaction, 10 −9 cm 3 s −1 , is an upper limit found experimentally by Mitchell et al (2005) Figure 13. Line surface brightness ratios relative to OH + 971 GHz versus the cosmic ray ionisation rate ζ in units of ζ 0 , for models with n H = 1900 cm −3 and a rate coefficient for ArH + + e − of 10 −11 cm 3 s −1 .…”

Section: Line While This Ohmentioning

confidence: 66%

“…The grid was rerun with reduced electron recombination rates of 10 −10 and 10 −11 cm 3 s −1 in order to investigate the effects on the abundance of ArH + . The highest gas temperature reached in any of the PDR models is around 12000 K, corresponding to a thermal energy of about 1.0 eV, while Mitchell et al (2005) found the reaction rate for electron energies below 2.5 eV was negligible. Figure 13 shows the relative line surface brightnesses versus ζ for a cloud density of 1900 cm −3 , this time with the ArH + + e − reaction rate set to 10 −11 cm 3 s −1 .…”

Section: Line While This Ohmentioning

confidence: 90%

See 1 more Smart Citation

Modelling the ArH+ emission from the Crab nebula

Priestley

Barlow

Viti

2017

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

We have performed combined photoionization and photodissociation region (PDR) modelling of a Crab Nebula filament subjected to the synchrotron radiation from the central pulsar wind nebula, and to a high flux of charged particles; a greatly enhanced cosmic ray ionization rate over the standard interstellar value, ζ 0 , is required to account for the lack of detected [C I] emission in published Herschel SPIRE FTS observations of the Crab Nebula. The observed line surface brightness ratios of the OH + and ArH + transitions seen in the SPIRE FTS frequency range can only be explained with both a high cosmic ray ionization rate and a reduced ArH + dissociative recombination rate compared to that used by previous authors, although consistent with experimental upper limits. We find that the ArH + /OH + line strengths and the observed H 2 vibration-rotation emission can be reproduced by model filaments with n H = 2 × 10 4 cm −3 , ζ = 10 7 ζ 0 and visual extinctions within the range found for dusty globules in the Crab Nebula, although far-infrared emission from [O I] and [C II] is higher than the observational constraints. Models with n H = 1900 cm −3 underpredict the H 2 surface brightness, but agree with the ArH + and OH + surface brightnesses and predict [O I] and [C II] line ratios consistent with observations. These models predict HeH + rotational emission above detection thresholds, but consideration of the formation timescale suggests that the abundance of this molecule in the Crab Nebula should be lower than the equilibrium values obtained in our analysis.

show abstract

Section: Line While This Ohmentioning

confidence: 66%

Section: Line While This Ohmentioning

confidence: 90%

Modelling the ArH+ emission from the Crab nebula

Priestley

Barlow

Viti

2017

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

show abstract

“…The latter number is the sum of the branching ratios of channels (RC8b) and (RC8c), to which we have assigned equal values. For DR of ArH + (RC9), there are apparently no data, with the exception of an upper limit of 1 Â 10 À9 cm 3 s À1 , which was measured by Mitchell et al (2005). We adopt this value as the thermal DR coefficient with the temperature dependence of T À0:5 e .…”

Section: Rate Coefficients For Specific Dissociative Recombination Rementioning

confidence: 99%

The chemistry of protonated species in the martian ionosphere

Fox

2015

Icarus

136

View full text Add to dashboard Cite

“…(8) Mitchell et al (2005b). (9) Unshielded rate based on theoretical cross-sections of Alexseyev et al (2007).…”

Section: Basic Features Of Argon Chemistrymentioning

confidence: 99%

Ubiquitous argonium (ArH⁺) in the diffuse interstellar medium: A molecular tracer of almost purely atomic gas

Schilke

Neufeld

Müller

et al. 2014

A&A

146

171

View full text Add to dashboard Cite

Aims. We describe the assignment of a previously unidentified interstellar absorption line to ArH + and discuss its relevance in the context of hydride absorption in diffuse gas with a low H 2 fraction. The confidence of the assignment to ArH + is discussed, and the column densities are determined toward several lines of sight. The results are then discussed in the framework of chemical models, with the aim of explaining the observed column densities. Methods. We fitted the spectral lines with multiple velocity components, and determined column densities from the line-to-continuum ratio. The column densities of ArH + were compared to those of other species, tracing interstellar medium (ISM) components with different H 2 abundances. We constructed chemical models that take UV radiation and cosmic ray ionization into account. , and HF column densities promises to be a faithful tracer of the distribution of the H 2 fractional abundance by providing unique information on a poorly known phase in the cycle of interstellar matter and on its transition from atomic diffuse gas to dense molecular gas traced by CO emission. Abundances of these species put strong observational constraints upon magnetohydrodynamical (MHD) simulations of the interstellar medium, and potentially could evolve into a tool characterizing the ISM. Paradoxically, the ArH + molecule is a better tracer of almost purely atomic hydrogen gas than H itself, since H can also be present in gas with a significant molecular content, but ArH + singles out gas that is >99.9% atomic.

show abstract

Dissociative recombination of rare gas hydride ions: II. ArH⁺

Cited by 38 publications

References 35 publications

Modelling the ArH+ emission from the Crab nebula

Modelling the ArH+ emission from the Crab nebula

The chemistry of protonated species in the martian ionosphere

Ubiquitous argonium (ArH⁺) in the diffuse interstellar medium: A molecular tracer of almost purely atomic gas

Contact Info

Product

Resources

About

Dissociative recombination of rare gas hydride ions: II. ArH+

Cited by 38 publications

References 35 publications

Modelling the ArH+ emission from the Crab nebula

Modelling the ArH+ emission from the Crab nebula

The chemistry of protonated species in the martian ionosphere

Ubiquitous argonium (ArH+) in the diffuse interstellar medium: A molecular tracer of almost purely atomic gas

Contact Info

Product

Resources

About

Dissociative recombination of rare gas hydride ions: II. ArH⁺

Ubiquitous argonium (ArH⁺) in the diffuse interstellar medium: A molecular tracer of almost purely atomic gas