High pressure x-ray absorption spectroscopy at lower energy in the dispersive mode:: application to Ce and FePO4

X-ray absorption spectroscopy (XAS) using a diamond anvil cell has been extended to lower energies (below 6 keV) thanks to smaller diamond anvils and to a new acquisition set-up on the energy dispersive x-ray absorption beamline of LURE. The valence change of Ce with pressure is followed at the L(III) edge of cerium up to 8 GPa together with the bond length variation during the same experiment. The pressure induced coordination change around the Fe atom in FePO(4) is determined at the Fe K edge through the pre-edge feature behaviour, the XANES modification and the Fe-O bond length increase.