Toward a Raman/FORS discrimination between Art Nouveau and contemporary stained glasses from CdSxSe1-x nanoparticles signatures

CdSxSe1-x quantum dots received considerable attention in academic studies and as cut-off filters and indirect-gap semiconductors. These later compounds have also been used for artistic purposes to produce colored glass since the 1920s thanks to their bright colors. Because non-invasive conditions are now mandatory when considering objects belonging to the cultural heritage, the use of Raman and fiber optics reflectance spectroscopy has been identified as potential ones to obtain information about the nanostructure of six samples of historical glass produced between the late 1920s and modern days. The average elemental composition of the nanocrystals has been deduced processing both optical and vibrational data, and the result arising has been compared taking into account the several factors affecting the experimental results. The diffusion of zinc inside the nanocrystals has also been questioned by the shift caused on the CdS- and CdSe-like phonon band wavenumber and on the absorption edge wavelength. An investigation of the size distribution and crystallinity of CdSxSe1-x nanoparticles has been also performed considering those parameters that are mainly influenced by the disorder of the system, such as the extent of the Urbach tail and the Raman bandwidth. Thanks to the results obtained, discrimination between the more recent glass and the older Art Nouveau ones has been verified, leading to the identification of a useful analytical protocol for conservation purposes. Copyright (C) 2015 John Wiley & Sons, Ltd.