X-Ray Absorption Spectroscopy Fingerprints for bcc and hcp Iron at Earth’s Core Conditions

The shapes of Fe K-edge of X-ray absorption spectra (XAS) were theoretically computed at Core conditions by using a number of molecular dynamics snapshots from a previously equilibrated iron system at 360 GPa and 7000 K. Reference fingerprints for the different iron polymorphs, namely Fe-bcc and Fe-hcp, were thus obtained within the multi-scattering method and therefore proposed as specific spectroscopic fingerprints. It is shown that is possible to unfold the long-standing controversy about the structural complexity of iron at the Earth’s inner core conditions. Specifically, high pressure studies from static laser heated diamond anvil cell and dynamic compression can take advantage of the proposed spectroscopic fingerprints.