Raman spectrometry is a method of vibrational analysis that gives structural information on the molecules composing the sample of the pictorial material. It consists in the analysis of the radiation emitted when the molecules are excited by a laser beam. This technique is based on the inelastic diffusion of light by the material. The analysis in non-destructive, without contact, without preparation of the sample. In general, this analysis is performed on samples but can also be done directly on paintings.
As it is molecular spectroscopy technique, it provides information on the functional groups that constitute the molecules, which facilitates the molecular identification of all the materials examined.
Raman is used for the identification and characterization of inorganic materials (pigments, corrosion products,…) and some organic materials (synthetic dyes and pigments, many natural dyes and pigments).