Gerd Schneider receives a professorship for "X-ray microscopy" at Humboldt-Universität zu Berlin
Prof. Dr. Gerd Schneider becomes a full professur for x-ray microscopy at the Humboldt University Berlin and is the head of the HZB group "Microscopy". © WISTA MANAGEMENT GmbH
On 29 April 2015, Gerd Schneider (HZB) accepted the call to a W2-S “X-ray microscopy” professorship at the Department of Physics of Humboldt-Universität zu Berlin. The professorship is associated with heading the workgroup “X-ray microscopy” at the Helmholtz-Zentrum Berlin für Materialien und Energie. With his group, the internationally recognised expert is developing new methods and applications for X-ray microscopy, which delivers crucial information for many scientific disciplines – from material and energy research to the life sciences.
The workgroup of Gerd Schneider operates one of the most advanced X-ray microscopes in the world, which allows spatial resolutions of down to ten nanometres using the “soft” X-ray light from BESSY II.
X-ray microscopy is an indispensable tool for studying materials
X-ray microscopy has decisive advantages over optical and electron microscopy: It allows researchers to observe objects in three dimensions, for example – and that at a very high resolution of 10 nanometres. “While researchers can only observe very thin samples of a maximum of about 0.1-µm thickness under the electron microscope, X-ray microscopy allows you to study entire cells of 10-µm thickness, for example. Compared to modern, super-resolution optical microscopy, which needs stain molecules inside cells to overcome the Abbé resolution limit, X-ray microscopy delivers a direct view to the cellular structures without any staining,” Prof. Gerd Schneider explains. Optical and X-ray microscopy therefore allow the study of whole cells, where correlative optical microscopy of individual cells can localise certain proteins whose distributions can be brought into a structural cellular context using X-ray microscopy.
Since every chemical element has specific X-ray absorption edges, X-ray microscopy can be used to determine the specific elements in the components of a sample. Even chemical bonding states can be clearly imaged using near-edge spectroscopy. Because the elements exhibit characteristic fluorescence under X-ray lights, one can also clearly determine the spatial distribution of extremely low concentrations of elements in a sample. In this way, X-ray microscopy delivers a comprehensive picture of each sample.
Developing high-precision lenses
Achieving the highest possible resolution in X-ray microscopy requires high-precision lenses to focus the X-ray beams. In addition to developing X-ray microscopes, Gerd Schneider’s workgroup has contributed greatly to the advancement of these lenses, known as Fresnel zone plates. Given such 3D X-ray lenses and modern synchrotron sources like BESSY II, great contributions can be made towards answering many scientific questions, from the fundamentals of structural biology to research into modern energy storage solutions.
- BESSY II: How intrinsic oxygen shortens the lifespan of solid-state batteriesAlthough solid-state batteries (SSBs) demonstrate high performance and are intrinsically safe, their capacity currently declines rapidly. A team from the TU Wien, Humboldt-University Berlin and HZB has now analysed a TiS₂|Li₃YCl₆ solid-state half-cell in operando at BESSY II using a special sample environment that allows for non-destructive investigation under real operating conditions. Data obtained by combination of soft and hard X-ray photoelectron spectroscopy (XPS and HAXPES) revealed a new degradation mechanism that had not previously been identified in solid-state batteries. They have gained some surprising insights, particularly regarding the harmful role played by intrinsic oxygen. This study provides valuable information for improving design and handling of such batteries.
- Spintronics at BESSY II: Real-time analysis of magnetic bilayer systemsSpintronic devices enable data processing with significantly lower energy consumption. They are based on the interaction between ferromagnetic and antiferromagnetic layers. Now, a team from Freie Universität Berlin, HZB and Uppsala University has succeeded in tracking, for each layer separately, how the magnetic order changes after a short laser pulse has excited the system. They were also able to identify the main cause of the loss of antiferromagnetic order in the oxide layer: the excitation is transported from the hot electrons in the ferromagnetic metal to the spins in the antiferromagnet.
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