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PhD defence Sandra Wiersma: the hidden life of cosmic carbon

Date of news: 8 March 2021

Wednesday March 17, Sandra Wiersma will defend her thesis on polycyclic aromatic hydrocarbons (PAHs), large carbonaceous molecules in the interstellar medium thought to be formed in outflows of dying stars. She was appointed at the University of Amsterdam and stationed at FELIX Laboratory, where she used the unique, high-intensity light to explore the properties of PAHs.

Wiersma studied their fragmentation and recorded infrared spectra of highly stable PAHs under astronomically relevant conditions, for the first time in the far-infrared. She also examined the way different heteroatoms, sizes and shapes influence both the IR spectra and fragmentation chemistry of the PAHs. Her work makes an important contribution to the knowledge on PAHs and how they change under high intensity.

“I loved my time at FELIX. I picked up many skills on different instruments - in that context, I do have to thank all the skilled technicians at FELIX that were always willing to help.  If it all works as it should, there is limited time to do your experiments, and then you have to be interpret the results, which is not always easy. I‘m pretty proud of what I accomplished. “

Sandra Wiersma is a familiar face at the FELIX Laboratory.  She did her a bachelor internship at FELIX under the supervision of Joost Bakker, where she studied the production of gas-phase platinum clusters in a molecular beam. “I came back to FELIX because of the research possibilities of course, but also because of the people. They really take an effort to create an open atmosphere. With social drinks, barbecues, the yearly Carnival celebration and so on.  I really felt part of the lab.”

sandra wiersmaWiersma in the lab, bringing PAHs into the gas phase

Postdoc Toulouse

Wiersma already started as a postdocoral researcher at the French research institute of astrophysics and planetology (IRAP) in Toulouse. She joined the group of Dr. Christine Joblin. Here she will study the reactions of silicon carbides with small, astrochemically relevant hydrocarbons. “All my interests now come together: astrochemistry, clusters and experimental challenges. I just can’t imagine anything more fun than this!”


Sandra will defend her thesis ‘The hidden life of cosmic carbon: Infrared fingerprint spectroscopy and fragmentation chemistry of gas-phase Polycyclic Aromatic Hydrocarbons'  on Wednesday, March 17 at 4 pm.

Promotor: prof. dr. W.J. Buma (UvA).
Co-promotors: dr. ir. A. Petrignani (UvA) and dr. J.M. Bakker (FELIX, RU).

Due to strict coronavirus measures her promotion will take place online.