Use of Mössbauer Spectroscopy in the Study of Ancient Pottery

Abstract

THE Mössbauer effect provides a useful technique for the determination of the oxidation state of iron and the symmetry of its immediate environment^1,2. This effect refers to the recoil-free emission and subsequent absorption of gamma radiation by similar nuclei. The two main parameters which may be derived from such spectra are the isomer shift, which is a measure of the s-electron density at the nucleus, and the quadrupole splitting, which is a reflexion of the electric field gradient at the nucleus. These two parameters provide information about the local symmetry around the iron atom and its oxidation state. Mössbauer spectroscopy provides the only available technique for the direct examination of solid samples which can give these results—wet methods provide no information about the iron lattice sites and oxidation states derived from such experiments are open to doubt. This approach has already proved its worth in the study of the silicate minerals, where these parameters have been studied for minerals of known structure containing substituted iron atoms, enabling a correlation to be established between these parameters and the iron sites and oxidation states².