Electronic structure of Fe/Mg carbonates at conditions of the Earth’s lower mantle: Implications for the formation of tetrahedrally coordinated carbon

Aim of this project is to reveal the electronic structure of iron in high-temperature high-pressure tetra-carbonate phases exploiting x-ray emission spectroscopy complemented by x-ray Raman scattering spectroscopy with focus on the iron’s spin state, the co-existence of high and low spin iron, and the role of iron’s ligands. Starting in the first phase of the project with ex-situ experiments on temperature quenched samples applying x-ray diffraction, optical Raman spectroscopy, x-ray absorption and emission spectroscopy, in-situ studies in the second part of the project will allow to analyze and identify the reaction paths that lead to formation of tetra-carbonate phases and their spins state using Kβ and valence-to-core emission spectroscopy. Therefore, an advanced spectroscopic setup will be developed to perform experiments at synchrotron radiation sources that combine diamond anvil cell with laser-heating and simultaneous detection of x-ray emission and x-ray Raman scattering in order to constrain the electronic structure of carbonate phases at lower mantle conditions.