Stratigraphic investigation of wall painting fragments from Roman villas of the Sabina area

A number of plaster fragments of Roman wall paintings have been investigated through micro-Raman and laser-induced breakdown spectroscopy in order to characterize the different layers of paint. The samples come from two Roman villas in the Sabina area, a countryside close to Rome. The two sets of painted plasters present different palette of colors, pictorial technique and texture as the villas are dated one in the first century A.D. and the other in the second. Both micro-Raman and LIBS spectroscopies have supplied compositional information by consuming a microscopic amount of sample material and not requiring sophisticated and expansive preparation of the plaster. Depth profile analysis has also been performed by monitoring the intensities ratio of specific emission lines related to some characteristic elements. The spectroscopic results have been integrated with microscopic and profilometric investigation of the samples, allowing to analyze the depth and morphology of the craters produced by the penetration of the laser pulses into the samples.