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

S T R U C T U R E O F M A T E R I A L S

In 2021, the Structure of Materials (SOM) group and their teams of external users endeavoured to carry out experiments despite the difficulties imposed by remote access. Fortunately, users were gradually allowed to travel to the ESRF to carry out experiments themselves. By the end of the year, we were almost in normal user operation and able to exploit the new Extremely Brilliant Source (EBS) with more challenging experiments. There are still some experiments carried forward from previous proposal rounds but, by the end of February 2022, nearly all of them should be completed.

Commercial services at SOM beamlines continued to occupy a sizeable proportion of beam time, with the majority of industrial experiments occurring on BM05 using topo- and tomography techniques. The increased flux and coherence from the EBS upgrade continues to benefit clients in fields from semiconductors to food science. In addition to commercial activities, BM05 was the birthplace of new technique Hierarchical Phase-Contrast Tomography (HiP-CT) (page 153). HiP-CT has been used to image the damage in organs of COVID-19 victims and is now at the heart of the Human Organ Atlas, where the multiscale imaging system has permitted the imaging of entire intact organs at resolutions from 25 µm, zooming in to a 0.5 µm ultimate resolution. This will be moved to BM18 in the future, where it will be possible to scan a complete human body with 25 µm resolution with localised scans down to the sub-micron level.

The dark field X-ray microscope on ID06-HXM offers unique insights into the crystal structure of materials on length scales from 100 µm down to 100 nm. Samples come from a wide range of materials, ranging from structural materials such as metals and alloys to functional materials such as ferroelectrics, to biominerals. A virtual workshop was held in May to seed the user community for this new instrument and to determine the needs of future users. Current users of ID06-HXM appreciated the presentation of J. Garriga on the development of a user-friendly data-analysis package (darfix) for dark-field X-ray microscopy. Together with R. Rodriguez Lamas, she will host a dedicated 1/2-day tutorial on dark-field X-ray microscopy data analysis at the

ESRF User meeting. ID06-HXM will continue user operation until October 2022, when the dark-field microscopy end-station will be transferred to EBSL2/ID03. The new beamline, fully dedicated to hard X-ray microscopy, will start commissioning in September 2023.

The materials science beamline ID11 offers a wide portfolio of experimental techniques. These include high- energy single-crystal up to microstructure imaging. The EIGER2 X CdTe 4M, installed last year, has been running at maximum speed (500 Hz) for the majority of the point- scanning experiments (3DXRD and XRD-CT) and the ID11 team has continued developing Python codes for fast integration and sparsification. New software tools have been significantly improved for parallel data-processing to keep pace with the detector frame rate. After the successful installation of the EIGER2 X 4M CdTe detector on the nanoscope station, improvements will include modifications of the 3DXRD station detector arm to offer the same speed and high dynamic range for diffraction experiments demanding bigger beam sizes and heavier setups. Other developments include the assembly of a Pt100 thermo-heater furnace for small samples, which can be employed in vacuum or under argon atmosphere.

The main areas of activity at ID15A are catalysis, battery science, and the study of glasses and other disordered systems. ID15A is optimised for the rapid acquisition of multi-dimensional, multi-resolution X-ray diffraction data on real devices. A wide range of integrated sample environments for in-situ/operando experiments is available: furnaces, cryostats, a potentiostat and a high- pressure gas-feed system. Ancillary equipment including an IR spectrometer and a mass spectrometer is also available. In 2021, a high-speed, high-efficiency, high- energy-resolution Mirion Ge-CMOS detector was installed. Combined with the high flux provided by EBS, and with KB focusing optics, it allows high-energy X-ray fluorescence mapping with sub-micron resolution at kHz rate.

BM18 progressively started operations, with its radiation test validated in October and the first tomography system successfully tested just before the winter shutdown with two detectors and a small tomography stage from LAB-motion