Structural study of laser shocked MgO using X-rays Absorption Near Edge Spectroscopy

MgO is one of the components of rocky materials, constituting the Earth's

and terrestrial planets mantles. Detailed description of his phase diagram

is essential to properly model interior structures and dynamics of these

planets [1]. We report first time-resolved X-ray absorption near edge

spectroscopy (XANES) investigation of warm dense MgO at multi Mbar

pressures. The results were obtained on the LULI 2000 at the Ecole

Polytechnique using a nanosecond beam to compress a sandwiched CH/MgO/C/CH

target and the picosecond beam to generate the X-ray source. With an

approach previously validated on Al, we obtained XANES data at a wide range

of temperature and density conditions. With the support of quantum molecular

dynamic simulations we show the MgO band gap closure mechanism and the local

structural properties of liquid MgO.