F. Carelli, T. Grassi, F. A. Gianturco
Context. The attachment of free electrons to polycondensed aromatic ring molecules (PAHs) is studied for a variety of such molecules with different numbers of condensed rings and over a broad range of electron temperatures, using a multichannel quantum approach. The calculations of the relevant cross sections are used in turn to obtain the corresponding attachment rates for each of the systems under study, and these rates are parametrized as a function of temperature using a commonly employed expression for two-body processes. Aims. The scope of this work is to establish from first principles the influence of their chemical properties on the efficiency of electron-attachment process for PAHs. Methods. Quantum multichannel scattering methods are employed to generate the relevant cross sections and hence the attachment rates. Results. The rates obtained for the present molecules are found to markedly vary within the test ensemble of the present work and to be smaller than the values currently used for the full class of PAHs when models of their evolutions in ISM environments are employed. The effects of such differences on the evolutions of chemical networks that include both PAH and PAH- species are analysed in some details and related to previous calculations.
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http://arxiv.org/abs/1207.2673
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