Research at the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL) on Transition Metal Oxides Contributes to Greater Understanding of Mineral Surface Interactions with Contaminants


For the first time, EMSL scientist Scott Chambers and postdoctoral associate Tim Droubay have determined the difference in electron energy levels (crystal field splitting) at the surface of three well-defined single crystals of different iron oxides: I-Fe2O3(0001), y-Fe2O3(001), and Fe3O4(001). Until this work, the actual energy difference at the surface of any transition metal oxide was not known. Knowing the differences between surface and bulk crystal field strength is important for obtaining a fundamental understanding of the reactivity of oxide and mineral surfaces. In turn, this fundamental understanding of specific mineral surface-site reactivities substantially improves reactive transport models of contaminants in geologic systems, and allows more effective remediation schemes to be devised. The EMSL molecular beam epitaxy (MBE) system was used to prepare the crystals, and high-energy-resolution x-ray photoemission, synchrotron radiation x-ray absorption spectroscopy, and first-principles atomic multiplet theory were used to analyze the samples. This work was funded by EMSP and will be submitted for publication in Physical Review B.