"Synchrotron FTIR Studies of Hydrogen in MgSiO3 Perovskite"

Heather Watson, Lawrence Livermore National Laboratory

The incorporation of even small amounts of OH in minerals may have drastic effects on many physical properties including electrical conductivity, seismic velocity, and rheology.  Using synchrotron based FTIR, we measured the OH stretching region in both Al,Fe-bearing and Al-bearing MgSiO3 perovskite samples at the NSLS U2A beamline.  We performed measurements on samples that had been quenched from multi-anvil runs at 25 GPa and 1800^oC, as well as in-situ measurements at high pressure in a diamond anvil cell on previously laser heated samples of enstatite and ringwoodite that had been transformed to perovskite and perovskite +MgO.  It was found that there is not significant H dissolved in MgSiO3 perovskite at conditions corresponding to the uppermost part of the lower mantle.