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S C I E N T I F I C H I G H L I G H T S

M A T T E R A T E X T R E M E S

The new Extremely Brilliant Source (EBS) has now been in operation for one year, and we are starting to see its very positive impact on the scientific output of the Matter at Extremes group. In parallel, an ambitious instrumental development program is still underway at the majority of the group s beamlines to optimally exploit the exceptional performance of the EBS.

The three X-ray diffraction (XRD) beamlines ID06-LVP, ID15B and ID27 benefit from the installation of state- of-the art detector systems. They allow the collection of powder and single-crystal XRD data of exceptional quality, which already greatly surpass those obtained with the former ESRF storage ring.

The nuclear resonance beamline, ID18, has completed the development of a hard X-ray spectrograph, an instrument that largely improves the energy resolution from ~0.6 meV to ~100 µeV while keeping nearly the same beam intensity. The first user experiment will take place at the beginning of the year 2022. The ID18 team is also finalising the development of the X-ray nanoscope that will provide a submicron beam for hyperfine spectroscopy both in time domain (nuclear forward scattering) and energy domain (synchrotron Mössbauer source), and for lattice dynamics (nuclear inelastic scattering). To complete this panel of techniques, focusing lenses have been installed on the

synchrotron Mössbauer source, which will result in an intensity increase by a factor of two.

The X-ray absorption spectroscopy (XAS) beamlines BM23 and ID24-ED have resumed user operation since January and December 2021, respectively. At the general- purpose EXAFS beamline BM23, more than 30 user and four industrial experiments were carried out in a variety of scientific fields, such as operando chemistry, environmental sciences, planetary sciences, materials science and fundamental physics. A variety of sample environments (cryostat, oven, high-pressure cells, and chemical reactor cells) are operational, including a state- of-the-art chemistry/catalysis setup. The upgraded micro- XAS station offers a high-precision, submicron positioning system and combined XAS and XRD detection systems. An automated sample changer is also available for industrial applications.

The refurbishment of the ID24 beamline consists of the conversion of the historical EDXAS-S branch into a high- brilliance XAS beamline (ID24-DCM) equipped with the ESRF double-crystal monochromator, while the EDXAS-L branch is optimised for fast time-resolved XAS applications with time resolution down to 100 picoseconds using an energy-dispersive scheme (ID24-ED). This instrument provides high-pulsed magnetic field capabilities and a unique dynamic compression platform using the newly implemented High Power Laser Facility (HPLF). The ID24-ED branch and the HPLF-I facility have resumed user operation. The first dynamic compression user experiments were performed in December 2021, coupling a 10 ns/50 J drive laser to the ID24-ED X-ray beam. The opening of the ID24-DCM branch to the user community is foreseen in December 2022. It will offer unique scientific opportunities for in-situ chemistry, micro-XAS/HERFD/ XES applications and ultra-high pressure/temperature XAS studies.