Photo: Volker Lannert / Uni Bonn
Foto: Volker Lannert/Uni Bonn

Chemistry with physical methods      

For her research, Jeannine Gleim studies supercritical chemical substances. It sounds more precarious than it actually is, yet it is spectacular all the same. A high-power laser is Jeannine's most important tool.

© Volker Lannert/Uni Bonn

Super-fast, super-precise, and super-modern – these words can sum up Jeannine Gleim's research at the Institute of Physical and Theoretical Chemistry. She wants to make chemical interactions visible as they are happening using state-of-the-art laser technology. In doing so, she moves on the border between physics and chemistry. Physics offer methods for measurement in the high-tech laser laboratory and chemistry the objects for examination with supercritical substances – also called fluids. They are called fluids because they can flow like liquids. These fluids are called supercritical because they are not really liquids. Their state of aggregation cannot be clearly assigned to the liquid or the gaseous state. And that is exactly what makes them so attractive.

© Volker Lannert/Uni Bonn

Molecules are not rigid entities. They are always in vibration. This is called oscillation. And that not only affects the molecule as a whole, but also its chemical bonds. Scientists can relatively easily measure the frequency with which the individual bonds vibrate. Jeannine used this knowledge for her master's thesis. With the help of infrared spectroscopy, Jeannine stimulated single bonds of a molecule. The infrared light used had exactly the same frequency as that of the bond. If she stimulated one bond, it affected the others within the same molecule, as well as the bonds between different molecules. What Jeannine found out is that in the supercritical phase, the mutual influence of the individual bonds of different molecules is weaker because the interactions between the molecules become weaker.

For her doctoral thesis at the Institute of Physical and Theoretical Chemistry, Jeannine goes one step further with the help of multidimensional infrared spectroscopy. The advantage is that Jeannine can simultaneously make several bonds oscillate and even observe the flow of energy within the molecule. Her high-power laser fires off super-short flashes of light that last only a few femtoseconds. A femtosecond is the trillionth part of a second - so incredibly fast that even the fastest chemical reactions or spontaneous movements of the molecule are almost frozen like in a photographic snapshot.

Jeannine is doing real pioneering work. Research with multi-dimensional infrared spectroscopy, also abbreviated as MDIR, still counts as fundamental research. But the potential is huge. Environmental technology, pharmaceutical industry, material science and even medicine could benefit from her work in the future. Similar high-resolution imaging techniques like MRI already exist, but MDIR has a decisive advantage - only it shows superfast interactions at the molecular level in real time.

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Free radicals and high-power lasers      

Research at the interface between physics and chemistry

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