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.
- Battery research with the HZB X-ray microscopeNew cathode materials are being developed to further increase the capacity of lithium batteries. Multilayer lithium-rich transition metal oxides (LRTMOs) offer particularly high energy density. However, their capacity decreases with each charging cycle due to structural and chemical changes. Using X-ray methods at BESSY II, teams from several Chinese research institutions have now investigated these changes for the first time with highest precision: at the unique X-ray microscope, they were able to observe morphological and structural developments on the nanometre scale and also clarify chemical changes.
- BESSY II: New procedure for better thermoplasticsBio-based thermoplastics are produced from renewable organic materials and can be recycled after use. Their resilience can be improved by blending bio-based thermoplastics with other thermoplastics. However, the interface between the materials in these blends sometimes requires enhancement to achieve optimal properties. A team from the Eindhoven University of Technology in the Netherlands has now investigated at BESSY II how a new process enables thermoplastic blends with a high interfacial strength to be made from two base materials: Images taken at the new nano station of the IRIS beamline showed that nanocrystalline layers form during the process, which increase material performance.
- Hydrogen: Breakthrough in alkaline membrane electrolysersA team from the Technical University of Berlin, HZB, IMTEK (University of Freiburg) and Siemens Energy has developed a highly efficient alkaline membrane electrolyser that approaches the performance of established PEM electrolysers. What makes this achievement remarkable is the use of inexpensive nickel compounds for the anode catalyst, replacing costly and rare iridium. At BESSY II, the team was able to elucidate the catalytic processes in detail using operando measurements, and a theory team (USA, Singapore) provided a consistent molecular description. In Freiburg, prototype cells were built using a new coating process and tested in operation. The results have been published in the prestigious journal Nature Catalysis.