100 ESRF

The beamlines of the Electronic structure, Magnetism and Dynamics group entered the commissioning phase with the new Extremely Brilliant Source (EBS) in early 2020 essentially unchanged after the long shutdown. Consequently, ID12, ID20, ID28 and ID32 were quickly ready to carry out user experiments after the restart. ID26 required additional commissioning time because the beamline made the transition to the new beamline instrumentation control software, BLISS, which allows the beamline to be run using scripts written in the Python programming language. This provides fantastic new possibilities for developing sophisticated measurement protocols and interfacing data acquisition and analysis with the large libraries that exist in Python. Staff and users will have to learn how to take full advantage of this new and exciting development.

During the past year, Crispy, the graphical user interface for spectroscopy calculations, developed at the ESRF and written in Python, has received a major rewrite of the internal components, which should greatly simplify the implementation of novel functionality. To give an example, these changes have made possible the addition of an interface that allows users to easily run calculations in the Jupyter notebook (using Python), bringing calculations closer to the data analysis infrastructure developed at the ESRF. Beamline control, data analysis and theoretical modelling thus seamlessly connect to one other.

During the first semester of 2020, the sample environment team designed and commissioned several high-temperature cells: two high- spatial-stability and high-temperature furnaces for ID01, a new cell for spectroscopy at ID26 and a high-temperature insert on ID12. Yves Watier and team also designed and assembled a new standardised temperature-control box for beamlines. A cryogenic line actuator, developed and printed in-house, has also been implemented on beamlines that have fixed He cryostat equipment. A brand-new sample changer for high-throughput fluorescence experiments was developed and will be installed during the winter shutdown on BM23. It is a clip-on module, easy to install and remove from the beamline. The robot has a storage capacity of 3500 samples in holders of 100 pellets. The sample support can be ordered as injected

plastic plates in large quantities for a very low price. The sample environment team have taken care of the mechanical development as well as electronic and robot programming.

A variety of dichroic effects exploiting circularly polarised X-rays are investigated at ID12: X-ray natural circular dichroism (XNCD) and X-ray magneto-chiral dichroism (XMXD) probe local chirality in non-centrosymmetric crystals (see D. Mitcov et al., page 116), whereas X-ray magnetic circular dichroism (XMCD) probes magnetic anisotropy in an element-selective manner (see J.-L. Liu et al., page 102). A new source of circularly polarised X-rays, a HELIOS- II-type undulator with lU = 42 mm, was installed on the ID12 straight section during the EBS shutdown. This new source is complementary to the two other helical undulators on ID12 and its first harmonics spans from 3.15 to 8 keV. The new EBS source has made it possible to obtain a nearly round beam of circularly polarised X-rays with a spot size of less than 5 microns. It has opened new opportunities for ID12 users to perform dichroic mapping of chiral and multiferroic domains in crystals using XNCD and XMXD, respectively, as well as to extend the high-pressure limits for XMCD measurements, in particular, in the tender X-ray range.

The EBS provides a bright and beautiful photon beam on ID20. The assembly of a new dispersive X-ray emission spectrometer in von-Hamos geometry is in full swing, and the beamline staff hope to make it available to all ID20 users in the second half of 2021. Using photons produced by the previous ESRF storage ring, Longo et al. investigated the influence of iron doping of a magnesium-aluminate spinel catalyst support on the activity of the support for heterogeneous catalysis (page 103). Application of X-ray Raman scattering (XRS) spectroscopy allowed the recording of absorption edges of O, Al, Mg and Fe in one session. G. Raimondi et al. used a combination of X-ray absorption fine structure (XAFS) measurements from BM26 and XRS spectroscopy at ID20 to derive a model for the structure and bonding in a barium ferrite, promising candidates for solid oxygen fuel cell cathodes (page 105).

The user programme on ID32 restarted at the end of August in remote-operation mode, with experiments on charge density waves in the cuprates, among others. The beamline looks forward to being able to fully support

ELECTRONIC STRUCTURE, MAGNETISM AND DYNAMICS