Raman spectroscopy of modern art: classification and identification of Azo-pigments

Micro-Raman spectroscopy (MRS) is an important molecular spectroscopic technique for the non-destructive examination of objects of art. In this work, Raman spectra of a number of Ate-pigments are presented, which are important artists' pigments in contemporary artefacts. The Ate-pigments, being a group of cheap pigments with good painting properties, form an important subgroup of pigments that became available to the artists at the end of the 19(th) and the beginning of the 20(th) century. A classification for these Ate-pigments is presented, which is based on their chemical properties, reflected in their molecular Raman spectrum. It is shown that a close spectral examination can help in assigning the unknown pigment to a class of pigments and thus assist in the identification of the painting material.