Spectroscopic parameters and rest frequencies of isotopic methylidynium, CH<sup>+</sup>

Müller, H. S. P.

doi:10.1051/0004-6361/201014398

Cited by 32 publications

(23 citation statements)

References 19 publications

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“…Relying on the "close-coupled" modelling, effective potential energy functions have thus been determined by fitting to the experimental data represented by their smoothed (Dunham fit) values obtained by Müller 34 and by the original P − R combination differences of the observed frequencies.…”

Section: Resultsmentioning

confidence: 99%

“…b) Electronic mail: spirko@marge.uochb.cas.cz. these analyses, Müller 34 has recently reanalyzed all the available laboratory spectral data of CH + in terms of a single set of the Dunham spectroscopic constants, and determined thus the reference (rest) spectral frequencies for all the molecular isotopomers. The aim of this study is to extend this knowledge of molecular states by determining their wavefunctions, and to allow thus for accurate evaluating of the associated transition moments and effective (state-dependent) molecular properties.…”

Section: Introductionmentioning

confidence: 99%

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Effective potential energy curves of the ground electronic state of CH+

Sauer

Špirko

2013

The Journal of Chemical Physics

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This study presents effective (mass-dependent) potential energy curves for the methylidyne cation, which reproduce highly accurately all the available spectral data and allow for evaluation of reliable ro-vibrational wavefunctions of the probed isotopomers. The ro-vibrational wavefunctions are then used to average ab initio calculated radial functions of the rotational g-factor and spin-rotation constants yielding rotational and vibrational matrix elements of these properties for specific ro-vibrational states or transition moments for all isotopomers. The results can be of use in answering open questions concerning the formation/destruction of CH(+) in the interstellar medium and in the assignment of Zeeman or hyperfine splittings in rotational spectra of CH(+).

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effective potential energy curves of the ground electronic state of CH+

Sauer

Špirko

2013

The Journal of Chemical Physics

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“…The rest frequencies are based on the Cologne Database for Molecular Spectroscopy (CDMS database, Müller et al 2005). In particular, the frequencies of the CH + 1-0 and 2-1 and 13 CH + 1-0 transitions are based on Müller (2010). Table 2 includes the observed line parameters for our line sample observed with HIFI, which have been corrected for main beam efficiencies based on Roelfsema et al (2012).…”

Section: Observations and Data Reductionmentioning

confidence: 99%

The chemistry of ions in the Orion Bar I. – CH⁺, SH⁺, and CF⁺

Nagy

Tak

Ossenkopf

et al. 2013

A&A

203

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Context. The abundances of interstellar CH + and SH + are not well understood as their most likely formation channels are highly endothermic. Several mechanisms have been proposed to overcome the high activation barriers, including shocks, turbulence, and H 2 vibrational excitation. Aims. Using data from the Herschel Space Observatory, we studied the formation of ions, in particular CH + and SH + in a typical high UV-illumination warm and dense photon-dominated region (PDR), the Orion Bar. Methods. The HIFI instrument on board Herschel provides velocity-resolved line profiles of CH + 1-0 and 2-1 and three hyperfine transitions of SH + 1 2 −0 1 . The PACS instrument provides information on the excitation and spatial distribution of CH + by extending the observed CH + transitions up to J = 6-5. We compared the observed line intensities to the predictions of radiative transfer and PDR codes. Results. All CH + , SH + , and CF + lines analyzed in this paper are seen in emission. The widths of the CH + 2-1 and 1-0 transitions are of ∼5 km s −1 , significantly broader than the typical width of dense gas tracers in the Orion Bar (∼2-3 km s −1 ) and are comparable to the width of species that trace the interclump medium such as C + and HF. The detected SH + transitions are narrower compared to CH + and have line widths of ∼3 km s −1 , indicating that SH + emission mainly originates in denser condensations. Non-LTE radiative transfer models show that electron collisions affect the excitation of CH + and SH + and that reactive collisions need to be taken into account to calculate the excitation of CH + . Comparison to PDR models shows that CH + and SH + are tracers of the warm surface region (A V < 1.5) of the PDR with temperatures between 500 and 1000 K. We have also detected the 5-4 transition of CF + at a width of ∼1.9 km s −1 , consistent with the width of dense gas tracers. The intensity of the CF + 5-4 transition is consistent with previous observations of lower-J transitions toward the Orion Bar.Conclusions. An analytic approximation and a numerical comparison to PDR models indicate that the internal vibrational energy of H 2 can explain the formation of CH + for typical physical conditions in the Orion Bar near the ionization front. The formation of SH + is also likely to be explained by H 2 vibrational excitation. The abundance ratios of CH + and SH + trace the destruction paths of these ions, and indirectly, the ratios of H, H 2 , and electron abundances as a function of depth into the cloud.

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“…The original articles for the line frequencies, Einstein coefficients, and collisional rates are CO (Flower 2001;Jankowski & Szalewicz 2005;Yang et al 2006;Wernli et al 2006), H 2 O (Barber et al 2006;Dubernet & Grosjean 2002;Faure et al 2004Faure et al , 2007Daniel et al 2011), O i (Abrahamsson et al 2007;Bell et al 1998;Chambaud et al 1980;Jaquet et al 1992;Launay & Roueff 1977), C ii (Flower & Launay 1977;Launay & Roueff 1977;Wilson & Bell 2002), CH + (Müller 2010;Lim et al 1999;Hammami et al 2009;Turpin et al 2010), OH (Offer et al 1994).…”

Section: Appendix A: Collisional Datamentioning

confidence: 99%

Nature of the gas and dust around 51 Ophiuchi

Thi

Ménard

Meeus

et al. 2013

A&A

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Context. Circumstellar disc evolution is paramount for the understanding of planet formation. The gas in protoplanetary discs large program (GASPS) aims at determining the circumstellar gas and solid mass around ∼250 pre-main-sequence Herbig Ae and T Tauri stars. Aims. We aim to understand the origin and nature of the circumstellar matter orbiting 51 Oph, a young (<1 Myr) luminous B9.5 star. Methods. We obtained continuum and line observations with the PACS instrument on board the Herschel Space Observatory and continuum data at 1.2 mm with the IRAM 30 m telescope. The spectral energy distribution and line fluxes were modelled using the physico-chemo radiative transfer code ProDiMo to constrain the gas and solid mass of the disc around 51 Oph. The disc vertical hydrostatic structure was computed self-consistently together with the gas thermal balance.Results. We detected a strong emission by atomic oxygen [O i] at 63 microns using the Herschel Space Observatory. The [O i] emission at 145 microns, the [C ii] emission at 158 microns, the high-J CO emissions, and the warm water emissions were not detected. Continuum emission was detected at 1.2 mm. The continuum from the near-to the far-infrared and the [O i] emission are well explained by the emission from a compact (R out = 10-15 AU) hydrostatic disc model with a gas mass of 5 × 10 −6 M , 100 times that of the solid mass. However, this model fails to match the continuum millimeter flux, which hints at a cold outer disc with a mass in solids of ∼10 −6 M or free-free emission from a photoevaporative disc wind. This outer disc can either be devoid of gas and/or is too cold to emit in the [O i] line. A very flat extended disc model (R out = 400 AU) with a fixed vertical structure and dust settling matches all photometric points and most of the [O i] flux.Conclusions. The observations can be explained by an extended flat disc where dust grains have settled. However, a flat gas disc cannot be reproduced by hydrostatic disc models. The low mass of the 51 Oph inner disc in gas and dust may be explained either by the fast dissipation of an initial massive disc or by a very small initial disc mass.

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Spectroscopic parameters and rest frequencies of isotopic methylidynium, CH⁺

Cited by 32 publications

References 19 publications

Effective potential energy curves of the ground electronic state of CH+

Effective potential energy curves of the ground electronic state of CH+

The chemistry of ions in the Orion Bar I. – CH⁺, SH⁺, and CF⁺

Nature of the gas and dust around 51 Ophiuchi

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Spectroscopic parameters and rest frequencies of isotopic methylidynium, CH+

Cited by 32 publications

References 19 publications

Effective potential energy curves of the ground electronic state of CH+

Effective potential energy curves of the ground electronic state of CH+

The chemistry of ions in the Orion Bar I. – CH+, SH+, and CF+

Nature of the gas and dust around 51 Ophiuchi

Contact Info

Product

Resources

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Spectroscopic parameters and rest frequencies of isotopic methylidynium, CH⁺

The chemistry of ions in the Orion Bar I. – CH⁺, SH⁺, and CF⁺