München 2004 – scientific programme

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MO: Molekülphysik

MO 3: Elektronische Überg
änge

MO 3.6: Talk

Monday, March 22, 2004, 12:15–12:30, HS 355

Jet-cooled neutral and cationic PAHs studied by cavity ring-down spectroscopy — •A. Staicu¹, O. Sukhorukov¹, G. Rouillé^2,3, E. Diegel¹, F. Huisken^2,3, and Th. Henning³ — ¹Astrophysikalisches Institut und Universitätssternwarte, Friedrich-Schiller-Universität Jena — ²Institut für Festkörperphysik, Friedrich-Schiller-Universität Jena — ³Max-Planck-Institut für Astronomie, Heidelberg

Polycyclic aromatic hydrocarbons (PAHs) are relevant molecules for astrophysics. It is expected that they are present in the interstellar medium (ISM), and they are considered as possible carriers of the diffuse interstellar bands (DIBs). To prove this, absorption spectra of PAHs under astrophysical conditions should be obtained. Collision-free environment and low temperatures similar to those encountered in the ISM can be obtained in the laboratory in supersonic jets. We have chosen cavity ring-down spectroscopy (CRDS) to measure direct absorption spectra of jet-cooled PAHs in their neutral and cationic form. The absorption spectra of anthracene, pyrene, and fluorene, corresponding to their electronic transitions in the UV spectral range, have been studied. On the other hand, the cations of small PAHs exhibit absorption bands in the visible range where DIBs are observed. First CRDS experiments on the cations of naphthalene and anthracene were successful and their results will be presented.