Simultaneous high pressure high temperature X-ray emission and diffraction at ID27, ESRF, revisiting the spin transition of magnesiosiderite

The recent upgrade of ID27 at the ESRF, included a portable Von-Hámos X-ray emission spectrometer for simultaneous x-ray emission spectroscopy (XES) that can be used in parallel to x-ray diffraction (XRD) experiments in diamond anvil cells (DAC), with and without laser-heating of the sample. This combined setup, built within the framework of the BMBF-funded ‘NanoExtrem-2’ project, will facilitate in-depth studies of structural and electronic properties under extreme conditions.

To test the XES-XRD setup, DAC experiments were conducted on a magnesiosiderite [(Mg_0.43Fe_0.55Mn_0.2)CO₃] up to 50 GPa. Si(111) and Si(110) analyser crystals were successfully used for measurements of the Kβ_1,3 emission spectrum. The experiments demonstrated that Kβ_1,3 can be acquired within 90 min at photon flux of 10¹² photons/s, using a 23.5 keV beam. At this energy XRD patterns with a maximum scattering vector Q = 6 Å^-1 could be collected within 30 sec. Reducing the energy to 15.6 keV enabled acquisition of Kβ_1,3 in just 30 min at the same photon flux, resulting in a threefold improvement in XES intensity. At this energy, XRD patterns with a maximum scattering vector of Q=3.3 Å^-1 could be collected in 30 seconds.

These results highlighted the potential of ID27 for advanced studies of materials under extreme conditions, paving the way for novel insights into the relation between electronic state and bulk structure of many sample systems that have emission lines at energies ≥ 7 keV.

Acknowledgements

We acknowledge the German BMBF for financial support: BMBF Verbundprojekt ‘NanoExtrem’ 05K19IP2 and ‘NanoExtrem2’ 05K22IP2.