Van Rooij obtained his PhD in 1999. His research focused on macromolecular imaging mass spectrometry, a technique that allows for the detailed visualisation of thousands of molecules in a single experiment. In those early days, it was unclear whether this was even possible. Heeren: “Lots of things were new, lots of things failed. We built the instruments ourselves and worked with new concepts, which in theory we always thought would be huge breakthroughs.” Van Rooij had his fair share of moments of despair. “At times I even questioned the laws of physics. Is what I see through the device really there?”

After his PhD, Van Rooij moved to the Dutch Institute for Fundamental Energy Research (DIFFER), then the Rijnhuizen Institute for Plasma Physics. Leaving mass spectrometry behind, he turned his attention to low-temperature plasma physics, the development of solar fuel and sustainable plasma chemistry. Meanwhile, Heeren made overtures to bring Van Rooij to Maastricht. “An environment like Chemelot needs his knowledge. Gerard fit perfectly with the profile of the Faculty of Science and Engineering.”

Baby steps

In Maastricht, Van Rooij is working on the transition of the chemical industry at Chemelot to electrical energy. Plasma allows for the electrical generation of very high temperatures, without which such a transition would be impossible. “We also think we can use plasma chemistry to control new circular processes, like the production of plastic from methane and fertiliser from air,” Van Rooij says. The social relevance of the research on sustainable plasma chemistry was the drawcard that ultimately lured him to Maastricht.

Five years after Van Rooij obtained his PhD, Heeren had his hoped-for breakthrough in imaging mass spectrometry. Since then, it has grown into a full-fledged field in which Maastricht University is one of two world leaders. “Gerard took the first baby steps, laying the foundation on which the M4I institute was eventually built,” Heeren says. The mass computer is primarily used for precision medicine and improved patient care, including the early detection of tumour cells and, recently, a large-scale international study of Parkinson’s disease. “Knowledge is important, but more important is its added value for patients, researchers’ careers and society,” Heeren adds.

“Ron is part of my central nervous system,” Van Rooij says. “I’ve always remembered his comment about setting his sights on a new research field every ten years. I found that very impressive, an eye-opener. I’ve now made the move to Maastricht too. I don’t intend to stay cocooned in my research, but to roll up my sleeves and get my hands dirty at Chemelot, as Ron does in the hospital. That’s where it’s all happening.” Heeren: “One thing I learnt from Gerard, perhaps indirectly, is to put myself as a supervisor to one side and give people the space to develop. If a study isn’t going to your liking, don’t try to take over. Don’t say anything, Gerard will be fine.”

However different their current fields, Heeren sees the same thread running through their careers. Both have evolved from the role of instrumentation physicist to socially engaged scientist. “Our research is about building instruments and developing methods to measure phenomena at the interface of physics and biochemistry.” Both operate at the forefront of science, and, in particular, both are driven to make a difference in society. “We have that in common, and perhaps also sparked it in each other. For Gerard, it’s about helping industry switch to sustainable energy, whereas mass spectrometry enabled me to transition to clinical care and healthcare.” This requires interdisciplinarity—for Heeren, the new way of doing science. “The clustering of physicists, chemists, biologists and doctors, who put their knowledge together to tackle a complex problem.” Now, they can both put their knowledge to good use in Maastricht.

By: Hans van Vinkeveen (text), Harry Heuts (photography)