XAS study of Mn, Fe and Cu as indicators of historical glass decay

We present here a study of historic glass decay by means of X-ray absorption spectroscopy (XAS). Transition metal cations incorporated in the glass as chromophores exhibit modifications of their oxidising state and chemical environment as the glass suffers a decay process. These modifications can be monitored by measuring X-ray absorption near edge structure, XANES, and extended X-ray absorption fine structure, EXAFS, spectra around a selected atomic species. We apply the technique here to glasses from different periods ranging from 1st century BC to 18th century, demonstrating that XAS provides an advanced tool for qualitative analysis of glass decay. In particular we have found that it is possible to establish a relationship between the oxidation state of Fe and Cu cations and the decay suffered by the glass. In contrast, our results indicate that the Mn oxidizing state is not directly involved in the glass decay of the studied samples.