Fe and V oxidation state in chromites formed within the fusion crust of ordinary chondrite meteorites

We propose to study the oxidation state of V and Fe in chromites [(Fe,Mg)(Cr,Al,Ti,V)2O4] formed within the fusion crust of ordinary chondrite meteorites and compare the results with chromites found in the interior of the meteorites. Micro-XAS data collected on the proposed samples can be investigated by comparing pre-edge peaks with those of model compounds with known Fe or V oxidation state and coordination number. The proposed beamline (ID21) is ideal to collect data on samples that display chromite crystals as small as 2-5 micrometres within the fusion crust. The expected results are important in studying the temperature-redox conditions of the incoming meteoroid during atmospheric passage, and also to compare experimental data on meteorites and ceramics obtained during heating experiments using induction heated plasma wind tunnels. For this proposal we plan to measure Fe- and V K-edge XANES data for three ordinary chondrites of H, L and LL group.