Electron-impact excitation of diatomic hydride cations I: HeH${}^{+}$, CH${}^{+}$, ArH${}^{+}$

Abstract

{\bf R}-matrix calculations combined with the adiabatic nuclei approximation are used to compute electron-impact rotiational excitation rates for three closed-shell diatomic cations, HeH${}^{+}$, CH${}^{+}$, ArH${}^{+}$. Comparisons with previous studies show that an improved treatment of threshold effects leads to significant changes in the low temperature rates, furthermore the new calculations suggest that excitation of CH${}^{+}$ is dominated by $\Delta J=1$ transitions as is expected for cations with a large dipole moment. A model for ArH${}^{+}$ excitation in the Crab Nebula is presented which gives results consistent with the observations for electron densities in the range $2-3\times 10^3$~cm${}^{-3}$.

MNRAS submitted 7 pages, 9 figures

References in corpus (6)

• Detection of a Noble Gas Molecular Ion, {36}ArH^+, in the Crab Nebula
• Ubiquitous argonium (ArH${}^{+}$) in the diffuse interstellar medium -- a molecular tracer of almost purely atomic gas
• Detection of extragalactic argonium, ArH${}^{+}$, toward PKS~1830$-$211
• Spatially extended OH+ emission from the Orion Bar and Ridge
• OH+ in astrophysical media: state-to-state formation rates, Einstein coefficients and inelastic collision rates with He
• Near threshold rotational excitation of molecular ions by electron-impact

Cited by in corpus (20)

• The Cologne Database for Molecular Spectroscopy, CDMS, in the Virtual Atomic and Molecular Data Centre, VAMDC
• State-to-state chemistry and rotational excitation of CH${}^{+}$ in photon-dominated regions
• Detection of vibrational emissions from the helium hydride ion (HeH${}^{+}$) in the planetary nebula NGC 7027
• Modelling the ArH${}^{+}$ emission from the Crab Nebula
• Herschel/HIFI Spectral Mapping of C${}^{+}$, CH${}^{+}$, and CH in Orion BN/KL: The Prevailing Role of Ultraviolet Irradiation in CH${}^{+}$ Formation
• Self-generated ultraviolet radiation in molecular shock waves II. CH+ and the interpretation of emission from shock ensembles
• Inelastic low-energy collisions of electrons with HeH${}^{+}$: rovibrational excitation and dissociative recombination
• Theoretical study of ArH+ dissociative recombination and electron-impact vibrational excitation
• Experimental determination of the dissociative recombination rate coefficient for rotationally-cold CH${}^{+}$ and its implications for the diffuse cloud chemistry
• Energy-transfer Quantum Dynamics of HeH${}^{+}$ with He atoms: Rotationally Inelastic Cross Sections and Rate Coefficients
• Observations and analysis of CH${}^{+}$ vibrational emissions from the young, carbon-rich planetary nebula NGC 7027: a textbook example of chemical pumping
• Exploring the Possibility of Identifying Hydride and Hydroxyl Cations of Noble Gas Species in the Crab Nebula Filament
• Electron-impact excitation of diatomic hydride cations II: OH${}^{+}$ and SH${}^{+}$
• Dissociative recombination of CH${}^{+}$ molecular ion induced by very low energy electrons
• Thermal and Resonant Emission of Dark Ages Halos in the Rotational Lines of HeH${}^{+}$
• Kinetic rate coefficients for electron-driven collisions with CH${}^{+}$: dissociative recombination and rovibronic excitation
• Fate and detectability of rare gas hydride ions in nova ejecta: A case study with nova templates
• Chemistry and ro-vibrational excitation of HeH${}^{+}$ in the Planetary Nebula NGC 7027
• ArH+ and H2O+ absorption towards luminous galaxies
• Laser-probing the rotational cooling of molecular ions by electron collisions