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Astron. Astrophys. 343, L49-L52 (1999)

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Letter to the Editor

Electronic spectra of cold gas phase PAH cations: Towards the identification of the Diffuse Interstellar Bands carriers

Philippe Bréchignac and Thomas Pino

Laboratoire de Photophysique Moléculaire, C.N.R.S. Université de Paris-Sud, Bâtiment 210, F-91405 Orsay Cedex, France (philippe.brechignac@ppm.u-psud.fr)

Received 27 November 1998 / Accepted 30 January 1999


An original experimental technique capable to produce electronic spectra of cold gas phase cations of large aromatic molecules, previously suggested as a family of potential carriers of Diffuse Interstellar Bands (DIBs), has been developed and put to work. This achievement is demonstrated with the spectrum of the D2[FORMULA]D0 electronic transition of the phenanthrene cation, C14H10+, in the near infrared. The results are compared with the spectrum of the same species isolated in a neon matrix, showing how the effect of this environment on the spectrum severely limits the capability of the matrix isolation technique for definite DIB assignments.

Key words: molecular data – ISM: molecules

© European Southern Observatory (ESO) 1999

Online publication: March 1, 1999