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.
- BESSY II: Phosphorous chains – a 1D material with 1D electronic propertiesFor the first time, a team at BESSY II has succeeded in demonstrating the one-dimensional electronic properties of a material through a highly refined experimental process. The samples consisted of short chains of phosphorus atoms that self-organise at specific angles on a silver substrate. Through sophisticated analysis, the team was able to disentangle the contributions of these differently aligned chains. This revealed that the electronic properties of each chain are indeed one-dimensional. Calculations predict an exciting phase transition to be expected as soon as these chains are more closely packed. While material consisting of individual chains with longer distances is semiconducting, a very dense chain structure would be metallic.
- Did marine life in the palaeocene use a compass?Some ancient marine organisms produced mysterious magnetic particles of unusually large size, which can now be found as fossils in marine sediments. An international team has succeeded in mapping the magnetic domains on one of such ‘giant magnetofossils’ using a sophisticated method at the Diamond X-ray source. Their analysis shows that these particles could have allowed these organisms to sense tiny variations in both the direction and intensity of the Earth’s magnetic field, enabling them to geolocate themselves and navigate across the ocean. The method offers a powerful tool for magnetically testing whether putative biological iron oxide particles in Mars samples have a biogenic origin.
- What vibrating molecules might reveal about cell biologyInfrared vibrational spectroscopy at BESSY II can be used to create high-resolution maps of molecules inside live cells and cell organelles in native aqueous environment, according to a new study by a team from HZB and Humboldt University in Berlin. Nano-IR spectroscopy with s-SNOM at the IRIS beamline is now suitable for examining tiny biological samples in liquid medium in the nanometre range and generating infrared images of molecular vibrations with nanometre resolution. It is even possible to obtain 3D information. To test the method, the team grew fibroblasts on a highly transparent SiC membrane and examined them in vivo. This method will provide new insights into cell biology.