Optical spectroscopy of interstellar and circumstellar molecules. A combined laboratory and observational study.

PhD ceremony: Ms. N. Wehres, 16.15 uur, Academiegebouw, Broerstraat 5, Groningen

Title: Optical spectroscopy of interstellar and circumstellar molecules. A combined laboratory and observational study.

Promotor(s): prof. A.G.G.M. Tielens, prof. H.V.J. Linnartz

Faculty: Mathematics and Natural Sciences

This thesis describes the identification of inter- and circumstellar molecules by combining laboratory and observational data. The focus is on transient, i.e. radical species.

State-of-the-art spectroscopic techniques, such as time-gated fluorescence and cavity ring-down spectroscopy, are used to search for spectral signatures of carbon chain radicals, like C₉H₃ and HC₇H, in a supersonically expanding plasma. These species have been proposed as potential carriers of diffuse interstellar bands. In addition, the fluorescence spectra are compared with emission spectra of the Red Rectangle proto-planetary nebula that have been recorded for different spatial off-sets with the ESO New Technology Telescope. The assignment of astronomical data, using the laboratory results, provides snapshots of the ongoing chemical evolution in space.

The majority of the data have been recorded in the Sackler Laboratory for Astrophysics (Leiden Observatory) and the Laser Center VU.