Non-invasive analysis of reference glass and historical mosaic tesserae by means of reflectance infrared spectroscopy

Within vibrational spectroscopy techniques, Raman is much more employed than infrared spectroscopy for the study of glassy materials belonging to cultural heritage. This could be due to both a less straightforward interpretation of the spectra and a more difficult application of the technique with portable instrumentations. Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) can be exploited in archaeometric investigations because portable and non-invasive. On the other hand, no systematic applications of this technique to historical glasses are found in the literature. This exploratory work reports the DRIFTS investigation of the Corning Archaeological Reference Glasses, widely used as references in the cultural heritage field, and of real case glass samples, with the aim of exploring the potential of this technique to gain information about their composition and alteration. The results, exploiting the association of portable X-ray Fluorescence (pXRF), and, where possible, of EDS microanalyses, are encouraging, setting the samples within a compositional range and highlighting spectral differences for the altered surfaces.