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.
- Spintronics at BESSY II: Domain walls in magnetic nanowiresMagnetic domains walls are known to be a source of electrical resistance due to the difficulty for transport electron spins to follow their magnetic texture. This phenomenon holds potential for utilization in spintronic devices, where the electrical resistance can vary based on the presence or absence of a domain wall. A particularly intriguing class of materials are half metals such as La2/3Sr1/3MnO3 (LSMO) which present full spin polarization, allowing their exploitation in spintronic devices. Still the resistance of a single domain wall in half metals remained unknown. Now a team from Spain, France and Germany has generated a single domain wall on a LSMO nanowire and measured resistance changes 20 times larger than for a normal ferromagnet such as Cobalt.
- Graphene on titanium carbide triggers a novel phase transitionResearchers have discovered a Lifshitz-transition in TiC, driven by a graphene overlayer, at the photon source BESSY II. Their study sheds light on the exciting potential of 2D materials such as graphene and the effects they can have on neighboring materials through proximity interactions.
- Alexander von Humboldt Foundation Grant for Dr. Jie WeiIn April, Dr. Jie Wei started his research work in the Helmholtz Young Investigator Group Nanoscale Operando CO2 Photo-Electrocatalysis at Helmholtz-Zentrum Berlin (HZB) and Fritz Haber Institute (FHI) of the Max Planck Society. Wei received one of the highly competitive Humboldt postdoctoral research fellowships and will pursue his two-year project under the guidance of the academic hosts Dr. Christopher Kley and Prof. Dr. Beatriz Roldan Cuenya.