Albers, ChristianSakrowski, RobinThiering, NicolaLibon, LéliaSpiekermann, GeorgKaa, Johannes M.Gretarsson, HlynurSundermann, MartinTolan, MetinWilke, MaxSternemann, Christian2024-07-082024-07-082023-04-04http://hdl.handle.net/2003/4258510.17877/DE290R-24420X-ray spectroscopy of iron-bearing compounds under high pressure and high temperature is an important tool to understand geological processes in the deep Earth. However, the sample environment using a diamond anvil cell complicates spectroscopic measurements and leads to long data acquisition times. We present a setup for resonant and non-resonant X-ray emission spectroscopy and showcase its capabilities for in situ studies at high pressure and high temperature. Spin-state imaging of laser-heated FeCO3 at 75 GPa via Kβ1,3 emission spectroscopy demonstrates the great potential of this setup with measurement times within seconds for robust spin-state analysis results. The results of Kβ1,3 emission spectroscopy of cold-compressed Fe2O3 reveal a two-step spin transition with the ζ-phase between 57 GPa and 64 GPa, having iron in different spin states at the different iron sites. The phase transition via ζ- to Θ-phase causes a delocalization of the electronic states, which is supported by 1s2p resonant X-ray emission spectroscopy.enJournal of analytical atomic spectrometry;38(5)https://creativecommons.org/licenses/by/3.0/530Article