X-ray spectroscopy under extreme conditions: exploring planetary interiors with the Extremely Brilliant Source of the ESRF

The new Extremely Brilliant Source (EBS) of the ESRF features an important increase in brilliance resulting in improved beam focusing capabilities at the spectroscopy beamlines BM23, ID24-DCM (double-crystal monochromator branch) and ID24-ED (energy dispersive branch). These beamlines have undergone a substantial refurbishment program that has resulted in highly-optimized XAS, XRF and XES setups and high-beam focusing capabilities down to 400 nm at ID24-DCM. At BM23 and ID24-DCM state-of-the-art static high P/T instrumentations including laser-heated, resistively-heated and cryogenically cooled diamond anvil cells are available, while at ID24ED a high power laser facility (100 J laser) has been installed for dynamic compression time-resolved XAS studies. State-of-the-art detection systems for complementary XES and XRF, XRD measurements are also available at these instruments. It includes high-energy resolution crystal analyzer systems, single-and multi-element SSD XRF detectors equipped with poly-capillary focusing optics and a Pilatus 1M diffraction detector. The upgraded beamlines BM23 and ID24 open up new opportunities for exploring matter at planetary interiors conditions and enable studying inhomogeneous materials such as natural rock samples under ambient and extreme P/T conditions [1]. For example, the detailed study of geochemically important trace elements embedded in chemically and structurally complex and highly absorbing matrices will become possible at higher dilution levels than before (down to 100 ppb at ID24-DCM) and with higher spatial and energy resolution [2]. The new instruments will also allow extending the reachable P/T domain for static and dynamic XAS experiments beyond those conditions prevailing in the Earths core, and probing heterogeneous samples, low Z elements and trace elements at such extreme conditions. In this contribution, we will provide information about the new capabilities of the XAS beamlines BM23 and ID24, give an overview of the first acquired results after the EBS upgrade and present the emerging scientific opportunities in Earth and Planetary sciences. [1] V Cerantola, A.D. Rosa, et al., Journal of Physics Condensed Matter, 33, 27 (2021) [2] M. Merkulova, O. Mathon, et al., ACS, Earth Space Chem. 3, 1905 (2019)