Spectroscopy of low and intermediate Z elements at extreme conditions: in situ studies of Earth materials at pressure and temperature via X-ray Raman scattering

ABSTRACT

X-ray Raman scattering spectroscopy is an emerging method in the study of low and intermediate Z elements' core-electron excitations at extreme conditions in order to reveal information on local structure and electronic state of matter in situ. We discuss the capabilities of this method to address questions in Earth materials' science and demonstrate its sensitivity to detect changes in the oxidation state, electronic structure, coordination, and spin state. Examples are presented for the study of the oxygen K-, silicon L- and iron M-edges. We assess the application of both temperature and pressure in such investigations exploiting diamond anvil cells in combination with resistive or laser heating which is required to achieve realistic conditions of the Earth's crust, mantle, and core.

KEYWORDS:

• X-ray Raman scattering
• inelastic X-ray scattering
• X-ray absorption
• high pressure research
• diamond anvil cell
• minerals
• glasses
• melts
• Earth materials
• spin transition
• bonding transition
• coordination transformation
• oxidation state
• electronic structure

Acknowledgments

We would like to thank K. Mende, A. Nyrow, Ch.J. Sahle, and C. Weis for providing experimental data. The stishovite and silica glass samples were kindly made available by N. Nishiyama. We thank V. Cerantola for preparing and handling the FeCO${}_3$ single crystal. We would like to acknowledge helpful discussions with S. Huotari, A. Nyrow, Ch.J. Sahle, C. Weis, and G.T. Seidler during preparation of this manuscript and express our gratitude to all collaborators that have been involved in and gave indispensable support to our studies. We thank the ESRF (beamline ID20, former ID16), PETRAIII (beamline P01), SPring8 and NSRRC of Taiwan (beamline BL12XU), and APS (beamline 20-ID) for providing synchrotron radiation.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was financially supported by the BMBF via projects 05K10PEC, 05K13PE2 (within FSP302), and 05K16PE1.