Temperature dependence of rotational excitation rate coefficients of C2H− in collision with He

Dumouchel, F.; Spielfiedel, A.; Senent, María Luisa; Feautrier, N.

doi:10.1016/j.cplett.2012.03.006

Cited by 20 publications

(29 citation statements)

References 31 publications

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“…Rate coefficients for the C 2 H − anion are larger by factors up to 3 than the corresponding coefficients for the C 2 H neutral radical, depending on the transitions and the temperature considered. This difference could be partly due to the larger depth well for C 2 H − -He than for C 2 H-He and also to the asymptotic dependence of the PESs which varies as R −6 and R −4 for C 2 H-He and C 2 H − -He respectively (Dumouchel et al 2012). Similar trend was found recently for CN − (Klos & Lique 2011).…”

Section: Comparison Between C 2 H-he and C 2 H − -He Rate Coefficientssupporting

confidence: 72%

“…Thus modeling of molecular emission requires excitation calculations using radiative as well as collisional rate coefficients with the most abundant interstellar species He and H 2 . Collisional studies of C 2 H and C 2 H − with He at low temperatures were performed recently and in this proceeding Dumouchel et al 2012), we try to understand the particular behavior of negatively charged species during collisions and compare negative ion rate coefficients with those of neutral associated species.…”

Section: Introductionmentioning

confidence: 99%

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Rotational excitation of small carbon chains by collisions with He in the ISM

Spielfiedel¹,

Dayou²,

Dumouchel³

et al. 2012

EAS Publications Series

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Abstract. Modeling of molecular emission from interstellar clouds requires the calculation of rate coefficients for excitation by collision with the most abundant species. Based on new highly correlated potential energy surfaces, rotational excitation of C2H and C2H− radicals in collision with He are investigated. C2H fine and hyperfine structure is taken into account. As already found for other systems, rate coefficients for the C2H − ion are larger by a factor up to 3 compared to the neutral species.

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Section: Comparison Between C 2 H-he and C 2 H − -He Rate Coefficientssupporting

confidence: 72%

Section: Introductionmentioning

confidence: 99%

Rotational excitation of small carbon chains by collisions with He in the ISM

Spielfiedel¹,

Dayou²,

Dumouchel³

et al. 2012

EAS Publications Series

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“…One sees that H 2 binds much more strongly to the ion than He, mainly because of the creation of the hydrogen bonding, and that HN + 2 binds more than HCO + . 12 For the isoelectronic ionic C 2 H − -He interaction, 15 the weak minimum lies at an angle of θ 72 • , slightly towards the C end of the anion, in contrast to both He-HCO + and He-HN + 2 .…”

Section: A Potential Energy Surfacementioning

confidence: 99%

“…13,14 The isoelectronic anion C 2 H − is known to be stable, closed shell, and its interaction with He has also been recently studied. 15 The isoelectronic species HCN/HNC are abundant organic molecules in many astrophysical environments, but being neutral, their chemical physics differs from the cationic species that we deal with here. Their interaction with para-H 2 , J 2 = 0, has been examined.…”

Section: Introductionmentioning

confidence: 99%

The HCO+–H2 van der Waals interaction: Potential energy and scattering

Massó

Wiesenfeld

2014

The Journal of Chemical Physics

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We compute the rigid-body, four-dimensional interaction potential between HCO(+) and H2. The ab initio energies are obtained at the coupled-cluster single double triple level of theory, corrected for Basis Set Superposition Errors. The ab initio points are fit onto the spherical basis relevant for quantum scattering. We present elastic and rotationally inelastic coupled channels scattering between low lying rotational levels of HCO(+) and para-/ortho-H2. Results are compared with similar earlier computations with He or isotropic para-H2 as the projectile. Computations agree with earlier pressure broadening measurements.

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“…In the literature, it is well established that anions of linear carbon chains are very stable structures (Rosmus & Werner 1984). In two previous papers, we have demonstrated that collisional rates of anions with permanent dipole moments are distinctly larger than those of their neutral patterns, which favour their detection (Dumouchel et al 2012; Spielfiedel et al 2012). Infrared intensities depending on transition dipole moments can be expected to be stronger than those of neutral species.…”

Section: Introductionmentioning

confidence: 87%

Structure and electronic spectra of the C anion

Hammoutène

Hochlaf

Senent

2012

Monthly Notices of the Royal Astronomical Society

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Ab initio calculations are employed for determining structures, spectroscopic parameters and transitions to the excited electronic states of the astrophysical relevant C anion, which is a potential intermediate of chemical processes involving carbon chains and polycyclic aromatic hydrocarbons. Calculations confirm the prominent stability of linear carbon chain anions which guarantees their formation. The lowest doublet potential energy surface of C displays six isomers, whereas in the lowest quartet potential energy surface, a unique minimum energy geometry is found. The most stable form is the linear anion l‐C (X2Πu) followed by the c‐C (X2A1’) at 9291 cm−1 above in energy, which presents a distorted D3h structure. The other isomers are also located at more than 9000 cm−1 above l‐C (X2Πu). For each isomer, a set of spectroscopic parameters including their equilibrium structures, rotational constants at equilibrium, harmonic wavenumbers, dipole moments and electron affinities are predicted. For linear C, eight electronic states lying below the electron detachment threshold, are computed. Four doublet electronic states, which play important roles in the C reactivity, lie below 2 eV. Spin–orbit constants for the upper electronic states of l‐C are predicted.

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Temperature dependence of rotational excitation rate coefficients of C2H− in collision with He

Cited by 20 publications

References 31 publications

Rotational excitation of small carbon chains by collisions with He in the ISM

Rotational excitation of small carbon chains by collisions with He in the ISM

The HCO+–H2 van der Waals interaction: Potential energy and scattering

Structure and electronic spectra of the C anion

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