X-ray absorption study of laser-shocked hematite (Fe2O3) and wüstite (FeO

Iron oxides play a major role in the mineralogy of deep Earth and Super Earth exoplanets. The recent discovery of unexpected Fe-O stoichiometries at high pressures (P) and temperatures (T) questions our knowledge of the actual oxidation state of iron at mantle conditions. X-ray Absorption Near Edge Structure (XANES) is highly sensitive to oxidation states and local environment and is thus particularly well-suited to tackle the question of spin transitions and valence state of iron under the very high pressures of planetary mantles. We propose to explore XANES at Fe K-edge of shock-compressed hematite (Fe2O3) and wüstite (FeO), the prototype Fe(III)- and Fe(II)-bearing iron oxide, for precising the nature of observed phase transitions, actual valence state of iron at high pressure, up to 500 GPa.