X-ray emission setup to study electronic structure of iron bearing compounds in situ at high pressure and high temperature

The determination of iron-bearing compounds’ electronic structure under high pressure and temperature (HPHT) conditions is pivotal to understand the chemistry, physics and dynamics of the Earth’s interior [1,2].

We present a setup for investigating the electronic structure of such compounds in situ at HPHT using (resonant) X-ray emission spectroscopy ((R)XES) and exemplify its capabilities showing results for hematite (α-Fe2O3) and siderite (FeCO3). Conditions up to 80 GPa and 3000 K were achieved using diamond anvils cells in combination with a portable double-sided laser heating setup exploiting an Yb:YAG laser [3,4] and the (R)XES spectra were acquired utilizing a wavelength-dispersive von Hámos spectrometer in combination with a Pilatus 100K area detector [5].

This setup allows measurements of a full emission spectrum in a single-shot fashion. In combination with high intense synchrotron radiation available at beamline P01 of Petra III and a dedicated diamond anvil cell loading scheme, the measuring time is shortened such that in situ iron Kβ XES makes spin state imaging viable and provides simultaneously access to the valence-to-core emission. Furthermore, the use of miniature diamonds [6] enables RXES measurements at the iron K edge yielding detailed information iron’s electronic structure and local environment.

[1] B. Orcutt et al. Deep Carbon (2019) [2] Y. Kono et al. Magmas under pressure (2018) [3] C. Albers et al. PRB 105 085155 (2022) [4] G. Spiekermann et al. JSR, 27, 414 (2020) [5] C. Weis et al. JAAS 34, 384 (2019) [6] S. Petitgirard et al. JSR 24 (2017)