EXAFS characterization of ferric oxyhydroxides

The EXAFS method has been used for investigating the local structures of ferric oxyhydroxides which are reaction products formed on an iron surface exposed to air or immersed in salt water. Fe K EXAFS spectra of two references of ferric oxyhydroxides, i.e. goethite and lepidocrocite, which are often detected as components of reaction products, have been also studied for comparison thereof. The two reference oxyhydroxides demonstrated different EXAFS spectra, which are interpreted based on the atomic local structures. Fe K EXAFS spectra and their radial distribution functions of the reaction products formed on an iron surface have been compared with those of the reference oxyhydroxides. This comparison shows that the ®rst and second nearest neighboring structures around ferric ions in the reaction products are different from those of the two references. These results indicate that the local structures around ferric ions in the reaction products are disordered, although the atomic local structures of Fe±O may be described as being local structural units. # 2001 Elsevier Science B.V. All rights reserved.