XANES, UV-VIS and luminescence spectroscopic study of chromophores in ancient HIMT glass

A series of Late Roman glass fragments belonging to the peculiar group called HIMT (High Iron Magnesium Titanium glass), coming from two archaeological sites in Northern Italy (Modena province and Galeata excavations) and from Catania Roman amphitheatre, were studied by XANES, UV-VIS and luminescence spectroscopies to determine the distribution of the oxidation states of the two chromophores Fe and Mn. The samples, characterized by different colour nuances, were previously chemically characterized. In all the ancient glass samples, Fe results to be mostly in the trivalent state. XANES data indicate that the prevalent Mn oxidation state is 2þ, however the presence of minor amounts of Mn3þ is clearly proved by UV-VIS investigations. The different spectroscopic techniques, used in a combined approach, allow for the interpretation of the apparent anomalous colour of some of the ancient glass samples.