Single-shot XAS on laser shock compressed Fe-rich alloys: Fe-Ni, Fe-Si and Fe oxides

Deep inside planets extreme material states can be found: pressures up to hundreds of GPa and temperatures up to thousands and ten thousands of K are common. From all planets, the Earth is most investigated, but open questions e.g. regarding the crystallographic structure and composition of the core material remain. The Earth’s core consists mostly of iron, supposedly in an alloy with a substantial amount of nickel. However, results from seismological studies suggest the presence of lighter elements (like H, C, O ,Si and S), too. Not only for geophysics but also for modelling terrestrial planets found in extrasolar systems, the study of the high-pressure high-temperature phase diagram of iron and its alloys is of importance.
Bright X-ray sources in combination with high-power optical laser provide unique possibilities for creating and probing such extreme material states and their properties in the laboratory. In 2018, the High Power Laser Facility (HPLF) at the European Synchrotron Radiation Facility (ESRF) has started to be established. High quality X-ray absorption spectroscopy of dynamically compressed matter together with additional shock diagnostics will give insight into structural and electronic changes of the material as well as will give information about generated temperatures and pressures. This talk presents results from first commissioning experiments at this new outstanding facility, where laser shock compressed high-energy-density states of iron and its alloys with nickel and silicon have been investigated via single-shot X-ray absorption spectroscopy at the iron K edge.