Dynamic measurements in liquids now possible in the laboratory
The dashed black lines mark the first thin liquid 'sheet' in which the molecules are dissolved. There are two nozzles in the upper part and a collecting vessel in the lower part (left image). Transmission image of the flat jet (centre image). X-ray spectrum of the solution on the CCD detector (right image). © HZB
A team of researchers in Berlin has developed a laboratory spectrometer for analysing chemical processes in solution - with a time resolution of 500 ps. This is of interest not only for the study of molecular processes in biology, but also for the development of new catalyst materials. Until now, however, this usually required synchrotron radiation, which is only available at large, modern X-ray sources such as BESSY II. The process now works on a laboratory scale using a plasma light source.
"Our laboratory setup now makes this measurement method available to a wider community," says HZB physicist Dr. Ioanna Mantouvalou, who drove the development together with partners from the Technische Universität Berlin, the Max Born Institute, the Physikalisch-Technische Bundesanstalt and the company Nano Optics Berlin. "In a first step, the laboratory measurements can also more precisely define where further analyses at synchrotron sources are useful and promising. This allows us to make better use of scarce resources," says Mantouvalou.
Time-resolved soft X-ray spectroscopy provides access to the properties of organic materials and is therefore ideal for studying dynamic changes in the electronic structure of individual elements in disordered systems. However, measurements of liquid solutions in which these molecules or complexes are dissolved are particularly challenging. They require a high photon flux and extremely low noise. Therefore, these experiments require usually large-scale facilities such as modern synchrotron light sources.
In contrast, the new laboratory instrument uses light from a plasma created by the interaction of an intense laser pulse with metal. The new instrument provides a time resolution of 500 picoseconds and allows a very "stable" detection. "We were able to demonstrate this in our study using two examples in an aqueous solution. We analysed the metal complex compounds [Ni(CN)4]2- and [Fe(bpy)3]2+," says Richard Gnewkow, first author and PhD student in Mantouvalou's team.
- The future of corals – what X-rays can tell usThis summer, it was all over the media. Driven by the climate crisis, the oceans have now also passed a critical point, the absorption of CO2 is making the oceans increasingly acidic. The shells of certain sea snails are already showing the first signs of damage. But also the skeleton structures of coral reefs are deteriorating in more acidic conditions. This is especially concerning given that corals are already suffering from marine heatwaves and pollution, which are leading to bleaching and finally to the death of entire reefs worldwide. But how exactly does ocean acidification affect reef structures?
Prof. Dr. Tali Mass, a marine biologist from the University of Haifa, Israel, is an expert on stony corals. Together with Prof. Dr. Paul Zaslansky, X-ray imaging expert from Charité Berlin, she investigated at BESSY II the skeleton formation in baby corals, raised under different pH conditions. Antonia Rötger spoke online with the two experts about the results of their recent study and the future of coral reefs.
- Energy of charge carrier pairs in cuprate compoundsHigh-temperature superconductivity is still not fully understood. Now, an international research team at BESSY II has measured the energy of charge carrier pairs in undoped La₂CuO₄. Their findings revealed that the interaction energies within the potentially superconducting copper oxide layers are significantly lower than those in the insulating lanthanum oxide layers. These results contribute to a better understanding of high-temperature superconductivity and could also be relevant for research into other functional materials.
- Electrocatalysis with dual functionality – an overviewHybrid electrocatalysts can produce green hydrogen, for example, and valuable organic compounds simultaneously. This promises economically viable applications. However, the complex catalytic reactions involved in producing organic compounds are not yet fully understood. Modern X-ray methods at synchrotron sources such as BESSY II, enable catalyst materials and the reactions occurring on their surfaces to be analysed in real time, in situ and under real operating conditions. This provides insights that can be used for targeted optimisation. A team has now published an overview of the current state of knowledge in Nature Reviews Chemistry.