Review: X-ray scattering methods with synchrotron radiation
Resonant X-ray excitation (purple) core excites the oxygen atom within a H2O molecule. This causes ultrafast proton dynamics. The electronic ground state potential surface (bottom) and the bond dynamics is captured by distinct spectral features in resonant inelastic X-ray scattering (right).
© Martin Künsting /HZB
Synchrotron light sources provide brilliant light with a focus on the X-ray region and have enormously expanded the possibilities for characterising materials. In the Reviews of Modern Physics, an international team now gives an overview of elastic and inelastic X-ray scattering processes, explains the theoretical background and sheds light on what insights these methods provide in physics, chemistry as well as bio- and energy related themes.
"X-ray scattering can be used to investigate and resolve a wide variety of issues from the properties and excitations of fuctional solids, to homogeneous and heterogeneous chemical processes and reactions or even the proton pathway during the splitting of water," explains Prof. Dr. Alexander Föhlisch, who heads the Institute Methods and Instrumentation for Research with Synchrotron Radiation at HZB.
The article gives an overview of experimental and theoretical results in the field of resonant scattering of tunable soft and hard X-rays. The focus is on resonant inelastic X-ray scattering (RIXS) and resonant Auger scattering (RAS). In the review, the authors outline the most important achievements from the last two decades at Synchrotrons up to the latest advances in time-resolved studies with X-ray free-electron lasers.
- Metallic nanocatalysts: what really happens during catalysisUsing a combination of spectromicroscopy at BESSY II and microscopic analyses at DESY's NanoLab, a team has gained new insights into the chemical behaviour of nanocatalysts during catalysis. The nanoparticles consisted of a platinum core with a rhodium shell. This configuration allows a better understanding of structural changes in, for example, rhodium-platinum catalysts for emission control. The results show that under typical catalytic conditions, some of the rhodium in the shell can diffuse into the interior of the nanoparticles. However, most of it remains on the surface and oxidises. This process is strongly dependent on the surface orientation of the nanoparticle facets.
- KlarText Prize for Hanna TrzesniowskiThe chemist has been awarded the prestigious KlarText Prize for Science Communication by the Klaus Tschira Foundation.
- Shedding light on insulators: how light pulses unfreeze electronsMetal oxides are abundant in nature and central to technologies such as photocatalysis and photovoltaics. Yet, many suffer from poor electrical conduction, caused by strong repulsion between electrons in neighboring metal atoms. Researchers at HZB and partner institutions have shown that light pulses can temporarily weaken these repulsive forces, lowering the energy required for electrons mobility, inducing a metal-like behavior. This discovery offers a new way to manipulate material properties with light, with high potential to more efficient light-based devices.