The Salerno Exultet: its characterisation by Raman and PIXE-α analyses

摘要

Two non-destructive techniques, Raman spectroscopy and particle induced X-ray emission (PIXE-α) spectrometry, were used for a complete connotation of the Salerno Exultet, an illuminated parchment dated back to 13th century. The Salerno Exultet exhibits several areas which have undergone restoration treatments during the years. The complete connotation of this masterpiece was necessary in order to identify and to distinguish the original and the added pigments. Owing to its dimensions, it has been impossible to analyse the Salerno Exultet directly under the microscope of our Micro-Raman spectrometer. We have therefore used optical fibres connected to a three axis micro-positioned measurement head mounted on a large metal frame. PIXE analysis was performed using the portable instrumentation set up by the INFN-LANDIS Laboratory, Catania, Italy. The combination of these two complementary techniques (Raman spectroscopy for molecular level information and PIXE-a for the elemental composition) allowed us to reveal a palette formed by lapis-lazuli, cinnabar, verdigris, earths (white, red, brown, green), organic lakes and chalk.