The investigators are undertaking velocity measurements on lower mantle constituents in order to better understand the impact of the high-spin to low-spin (HSLS) electronic transition on lower mantle seismic profiles. They will measure velocities using Impulsive Stimulated Light Scattering on samples loaded in diamond anvil cells. The team seeks to characterize derivatives in velocity of ferro-periclase caused by changes in electronic configuration, iron content, temperature and pressure. These results will be interpreted within the context of Earth's deep mantle through further extension and application of the theory for the transition. Ultimately, elastic constants for ferro-periclase should be measured under mantle conditions of temperature in excess of 1000K as well as pressure. However, a reasonable goal in the near term will be to undertake high-pressure studies under modest conditions of heating and cooling. A quantitative validation of predictions under experimentally accessible conditions of temperature would lend confidence in the extrapolation to mantle temperatures. The successful characterization of elastic properties through the HSLS transition in iron-bearing silicate perovskites remains a longer term goal. Challenges include obtaining samples of sufficient quality to undertake the experiments. The project includes training of a graduate student.
