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Structure and electronic spectra of the Cinline image anion


  • D. Hammoutene,

    Corresponding author
    1. Laboratoire de Thermodynamique et Modélisation Moléculaire, Faculté de Chimie, USTHB, BP 32, El Alia, 16111 Bab Ezzouar, Alger, Algeria
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  • M. Hochlaf,

    Corresponding author
    1. Université Paris-Est, Laboratoire de Modélisation et Simulation Multi Echelle, MSME UMR 8208 CNRS, 5 Boulevard Descartes, 77454 Marne-la-Vallée, France
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  • M. L. Senent

    Corresponding author
    1. Departamento de Química y Física Teóricas, Instituto de Estructura de la Materia, IEM-C.S.I.C., Serrano 121, Madrid 28006, Spain
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E-mail: (DH); (MH); (MLS)


Ab initio calculations are employed for determining structures, spectroscopic parameters and transitions to the excited electronic states of the astrophysical relevant Cinline image 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 Cinline image 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-Cinline image (X2Πu) followed by the c-Cinline image (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-Cinline image (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 Cinline image, eight electronic states lying below the electron detachment threshold, are computed. Four doublet electronic states, which play important roles in the Cinline image reactivity, lie below 2 eV. Spin–orbit constants for the upper electronic states of l-Cinline image are predicted.