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Astron. Astrophys. 319, 318-330 (1997)

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The PAH hypothesis: a computational experiment on the combined effects of ionization and dehydrogenation on the IR signatures *

F. Pauzat , D. Talbi and Y. Ellinger

Equipe d'Astrochimie Quantique, Laboratoire de Radioastronomie Millimétrique, Ecole Normale Supérieure et Observatoire de Paris, 24 rue Lhomond, F-75231 Paris Cedex 05, France

Received 13 November 1995 / Accepted 22 July 1996


IR spectra of anthracene and pyrene derivatives, serving as models for isolated, linear and isolated, compact PAHs, respectively, have been calculated using ab-initio quantum mechanical methods. The separate and combined effects of ionization and multiple dehydrogenation have been studied. This study confirms and refines the trends of our preliminary paper on the smallest possible PAH, naphthalene. If small PAHs are responsible for any UIR bands, they should be ionized and partially dehydrogenated, with a few triple bonds at the periphery of the carbon skeleton.

Key words: molecular data – molecular processes – ISM: molecules – infrared: ISM: lines and bands

* Appendix A is only available in electronic form at CDS via http://cdsweb.u-strasbg.fr/abstract.html

© European Southern Observatory (ESO) 1997

Online publication: July 3, 1998