Electron angular distributions and attachment rates in o-Benzyne and Phenyl aromatic molecules: the effect of the permanent dipoles*
Department of Chemistry and CISM, The University of Rome
‘Sapienza’, P.le Aldo Moro
Received: 22 July 2013
Received in final form: 31 August 2013
Published online: 17 December 2013
Free, gas-phase polycyclic aromatic hydrocarbons (PAHs) and related species are currently considered to play an important role in the interstellar/circumstellar medium as they are thought to significantly contribute to both Diffuse and Unidentified infrared interstellar bands. They are also considered fundamental blocks of the interstellar dust and several formation mechanisms were proposed with regard to their interstellar/circumstellar synthesis. In this paper we therefore present and discuss the results obtained from ab initio quantum scattering calculations of the response from neutral polar aromatic single-ring species to low-energies electron collisions. Our main purpose is here to provide new values for the rate constants for electron attachment to orthobenzyne and to phenyl molecules by discussing in detail the effects of the long-range dipole interaction in the framework of the Born perturbative approximation at the first order. We shall further discuss the specific behavior of the electrons’ diffusion by such molecules, especially in the low-energy range of the scattered particles’ energies as guided by their permanent dipole moments. We shall also provide accurate numerical fittings for both rates and give explicitly the fitting parameters for their possible use in evolutionary models.
© EDP Sciences, Società Italiana di Fisica and Springer-Verlag 2013