IR and Raman spectroscopies, a way to understand how the Roman window glasses were made?

Two processes are known to make panes in West Europe during the Roman period: they may be cast on a flat surface or manufactured by the cylinder-blown process. The aim of our research is to give physico-chemical arguments to distinguish between both methods by using IR and Raman spectroscopies and to determine the fictive temperature T_f of the archaeological samples. The position of the 1050 cm^-1 band in the IR reflection spectra of annealed samples versus T_f has been studied, giving a calibration curve to determine the T_f of the archaeological sample. Both, the position of the 1100 cm^-1 Raman band and the ratio of the Q²/Q³ Raman bands intensities are also studied as a function of T_f for annealed samples. The T_f of both production methods is different. Our research favours the argument that the panes were produced by the cast method.