PhD defence Julianna Palotás: infrared spectroscopy of ionized fullerene derivatives: The astrophysical implications of breaking symmetries

26 April, Julianna Palotás successfully defended her thesis that is devoted to the laboratory aspects of astrochemistry. Despite its conceived emptiness, interstellar space is full of atoms, molecules and particles in large variety.  The exact composition is still being explored. This can tell us more about the physical conditions in the different regions. And if we understand the astrochemistry itself, we can learn more about the chemical evolution in space and, eventually, the chemical origin of life.

In her dissertation, Palotás focused on the infrared fingerprints of large carbonaceous molecular ions that are hypothesized to occur abundantly in interstellar environments: fullerenes and polyaromatics. With the tunable light of our free-electron lasers, she succeeded in recording the first laboratory infrared spectrum of protonated fullerenes C₆₀H⁺ and C₇₀H⁺.  To do so, she used mass spectrometry combined with infrared spectroscopy. By measuring the infrared wavelength-dependent fragmentation of ions, Palotás could record spectra of gaseous ionized species, which is very challenging with direct absorption measurement. The added proton breaks the high symmetry of C₆₀ producing a much richer infrared spectrum. Comparing the fingerprint of C₆₀H⁺ to emission spectra from nebulae associated with high C₆₀ abundances, she concludes that C₆₀H⁺ is a plausible contributor to their infrared emission. Furthermore, her research shows that the infrared spectra of ionized fullerenes are significantly distinct from the fingerprints of (ionized) polycyclic aromatic hydrocarbons, another prominent family of carbonaceous molecules known to be present in the interstellar medium. Her research offers new insights in the composition of the interstellar medium and provides starting points for further research.

Supervisor: prof. dr. J. Oomens
Copromotor: dr. G. Berden

The thesis cover shows a fullerene and a part of the Tarantula Nebula in the background

Challenging experiments

Palotás started at HFML-FELIX after studying Physics in Budapest. “I am driven by a will to understand everything about the world we live in, what surrounds us. It is all so fascinating. Then again, if you learn something new, you also know more about what we don’t understand yet. I enjoy experimental research: working with my hands, playing around in the laboratory. Challenging scientific experiments are therefore the perfect combination for me. There’s no possible way to hide; you really have to understand the theory and be able to translate it to your experiment. You have to know exactly what you are doing.”

EUROPAH network

As a PhD candidate, Palotás was a member of the EUROPAH network, funded by Marie Sklodowska-Curie Innovative Training Networks. The scientific goal of the network is to understand the role that polycyclic aromatic hydrocarbons play in the physics and chemistry of the interstellar medium. The European consortium consists of 3 companies and 13 research groups at 10 universities. She visited Cologne, Bristol and Aarhus. “The network gave me the opportunity to learn different techniques and work with many amazing people. The experiences I earned will certainly come into use in my next career step.”

Julianna Palotás (right) and the Doctorate Board at the defence

Career

Julianna Palotás starts in May as a postdoc in the Dodson group at the University of Maryland, USA. The focus of the research group is developing experimental tools to investigate the chemistry of the interstellar medium and planetary atmospheres.