Photoemission and electronic structure of FeOOH: Distinguishing between oxide and oxyhydroxide

Valence-band and core x-ray-photoemission spectroscopy has been used to examine the electronic structure of FeOOH and Fe₂{O}₃. The known small difference in the core-level Fe 2p spectra of the two compounds is discussed. Xα calculations of an{FeO}₆H₃^3- cluster are shown to give good agreement with the two-peak FeOOH valence-band XPS spectrum, and it is clear that FeOOH and Fe₂{O}₃can be clearly distinguished in the valence-band region. Xα calculations of an{FeO}₆^{9{{-}}}$ cluster are found to predict the three-peak structure of the ${Fe}₂O₃ valence band. The O 2s region of FeOOH is found to be more sensitive to chemical environment than the O 1s region, and the former region is well explained by the X{α} calculation. Little decomposition of FeOOH is found during data collection.