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Jolijn Onvlee: 'I am fascinated by studying small molecules and atoms at the highest possible level of detail’

Interview with dr. Jolijn Onvlee (Spectroscopy of Cold Molecules)

In September 2020, Jolijn Onvlee was appointed Assistant Professor in the Spectroscopy of Cold Molecules (SCM) department within the Institute for Jolijn OnvleeMolecules and Materials (IMM) at Radboud University. In her group she studies reactive collisions between individual molecules and atoms in the gas phase in order to unravel the functioning of molecular interactions and chemical reactions, using state-of-the-art experimental techniques such as the Zeeman decelerator and Velocity Map Imaging. Onvlee knows the Faculty of Science very well, as she studied and finished her PhD here. After working in Germany for a postdoctoral study, she returned to the Radboud University in her new role.

Jolijn Onvlee lives in the Betuwe region, together with her partner.

We interviewed Jolijn Onvlee about her research background, her research focus within IMM and herself.

Where exactly did your curiosity for science start?

“From an early age I have been fascinated by how things work in our world. I used to ask a lot of these ‘why’ questions, for instance to my grandfather when spotting birds. I always wanted to know why things happen; in nature, in space, everywhere around us.”

What did you study?

“At secondary school, I had a broad interest. Although I enjoyed many courses, I decided to continue in science. I studied Science and specialized in physical chemistry. Next to working in the lab, I liked computational chemistry. My first master internship was a combination of experimental and theoretical work in the Molecular and Laser Physics group of Professor Dave Parker and the Theoretical Chemistry department of Professor Gerrit Groenenboom. I also did a joined experimental and theoretical internship at the Solid State Chemistry department with Hugo Meekes and the Theoretical Chemistry department with (current professor) Herma Cuppen. I discovered that I enjoy most to study fundamental chemical processes with physical methods.”

You have done your PhD research at IMM. Tell us about it.

“During my master's internship in Parker's group, (current professor) Bas van de Meerakker started his own group. When he asked me for a joined PhD position with Gerrit Groenenboom - theoretically as well as experimentally oriented - I enthusiastically took this opportunity. In my PhD research I studied collisions of molecules and atoms, in order to look at them in the highest possible detail. A lot of research is done about how molecules and atoms collide, but we wanted to unravel it in every detail. The aim was to gain a better understanding of what is really happening when molecules and atoms collide. We used the Stark decelerator and Velocity Map Imaging; by combining these two techniques, we were able to measure with very high resolution. The research required theory, which I did together with Professor Gerrit Groenenboom and Professor Ad van der Avoird (emts). We have been able to observe the wave nature of colliding molecules. We also investigated cold collisions and resolved resonances. We gained a lot of knowledge and we have become a lot wiser.”

On your career path, you must have encountered difficulties as well. Could you give an example?

“Yes I did; I really liked combining theory and experiments. At the same time it was also challenging. It asked a lot of time and energy and many different people wanted my attention. That was quite challenging. Ultimately, it worked out and I learned about my boundaries and how to better deal with this.”

What did you do after your PhD?

“After my PhD, I worked as a postdoctoral researcher at DESY in Germany for 3.5 years. I have worked in the group of Professor Jochen Küpper. I studied ultrafast molecular processes, which we resolved as function of time. DESY is actually a large inspiring campus embedding physics, chemistry, and biology. I mainly did experimental work. The departments were large and broad; you learn a lot about many things, but going into depth with your research was in my opinion more difficult.”

How did you experience your time abroad?

“Living in Germany was fun and a great learning experience. I now better appreciate the more horizontal organizational structure in Dutch organizations and companies. I enjoyed it, had nice colleagues, and I have good contacts there now.”

How did you end up at Radboud University?

“My postdoc period was temporary. Besides that, I really wanted to return to the Netherlands. For me, Nijmegen is simply the best place for my kind of research. I applied on one of the vacant Christine Mohrmann fellowship positions. In September 2020 I started as an Assistant Professor in the Spectroscopy of Cold Molecules department.”

What is your research focus now?

“I have taken over one of the labs of Bas van de Meerakker. In this laboratory we use a Zeeman decelerator with magnetic fields to control molecules. I will focus on reactive collisions to study what is happening during chemical reactions; what happens when chemical bonds break and new bonds are formed? I use the Zeeman decelerator for that to unravel the reactions in high detail. If we know what exactly occurs in these chemical reactions, the next step is to control them. This research may lead to all kinds of applications; it can be used to better understand combustion and processes in space, but it can ultimately also help to make new materials. A PhD student and postdoc are currently working in the lab and we will recruit a new PhD candidate soon. Of course, bachelor and master students are very welcome to contribute to our research.”

Impression of a reactive collision

How did you experience starting in these difficult Corona times?

“In the first lockdown period I did not work at Radboud University yet. I started when there were less restrictions and we were allowed to come to the lab. But it was still a quite difficult time; many people worked from home, and it was less easy to drop by to ask questions or to brainstorm. I especially miss the ‘talks at the coffee machine’.”

You started with teaching. Partly online. How did that go and how was it for you?

“Indeed. Since November I have been teaching to second-year Physics students on the subject Electromagnetism. The combination of teaching hybrid (some students in the room, some join via Zoom) for the first time, the preparations and solving the technical issues was quite a challenge. I have figured out a lot by myself, but I succeeded and I am doing fine.”

What makes you happy being in the lab all day?

“Small molecules and atoms! Predicting what will happen at a very detailed level and at the same time testing it very accurately by doing experiments. Being able to find pieces of the puzzle and solve the puzzle, that gives me energy. In my daily work I also like writing a piece of the code in order to do better experiments. But mainly, solving problems together in a research team.”

What are your future plans in terms of research?

“We hope to be able to see the first reactive collisions shortly. This will be the first time in Nijmegen, how cool is that! We will look at small molecules and atoms - diatoms that react with an atom. We hope to obtain a higher resolution - using a Zeeman decelerator – and to study the reactions at low temperatures and in unexplored regimes.”

What is the societal relevance of your research?

“Chemical reactions are essential in the formation of new materials or molecules. The aim is to understand and control them. On the long term we can also apply these studies to processes in space; very cold reactive collisions help us to learn about what is happening in space.”

How do you experience IMM?

“I enjoy working at the IMM. I like the horizontal structure within our institute and the interdisciplinary research opportunities with other IMM groups. There is a friendly atmosphere at IMM. Although IMM employs many scientists, it feels like a small institute and I get to know people easily, although the lockdown makes that more challenging now. I returned in a different position and I have a different role now, but it still feels like coming home. What I specifically appreciate is that I can be myself and that my opinion is very much respected.”


Text: Miriam Heijmerink