Reduction of an α-Fe2O3(0001) Film Using Atomic Hydrogen

The α-Fe 2 O 3 (0001) biphase surface consists of an ordered arrangement of FeO(111) and α-Fe 2 O 3 (0001) surface domains on a Fe 2 O 3 bulk [N.G. Condon et al., Phys. Rev. Lett. 75, 1961, 1995]. The interaction of atomic hydrogen H at with this surface has been investigated at room temperature (RT, 300 K) by means of low-energy electron diffraction, X-ray photoelectron spectroscopy, and thermal desorption mass spectroscopy. The surface is easily hydroxylated by H at . Upon heating, the OH groups react to produce hydrogen and water, the latter of which results in the partial reduction of the surface. In a parallel but slower process, bulk reduction proceeds already during exposure at RT. First, Fe 3 O 4 (111) domains, embedded in the α-Fe 2 O 3 (0001) matrix, are formed. Finally, the film is completely reduced to Fe 3 O 4 . Further reduction toward FeO or metallic Fe appears kinetically hindered and is not observed under the low exposures used in our experiments.