Molecular techniques
Fourier Transform Infrared Spectroscopy
The application of infrared spectroscopy to art samples obtains both the class and composition of organic materials found in works of art (such as those of drying oils, resins, proteins and others) and mineral materials (such as colors, fossil, etc.) or mixtures thereof.
Infrared spectroscopy relies on the interaction of matter with infrared light. The various materials absorb different amounts of different infrared wave length depending on the chemical bonds present in the test sample. This absorption or reflection is recorded in the form of a spectrum.
It is possible to analyze multilayer samples taken in the form of a cross section, but this requires the use of a Micro-FTIR.
The interpretation of the spectra of unidentified samples in the spectrum are based on a comparison of this spectrum with spectra of known samples stored in digital libraries.
RAMAN Spectroscopy Raman scattering is a spectroscopic technique that is complementary to infrared absorption spectroscopy. With Raman spectroscopy it is possible to identify organic materials used in art such as a variety of proteins (animal glue, egg), drying oils (linseed), polysaccharides (gum arabic), etc. It can be applied locally on the surface of a work of art. It is also possible to use it in identifying inorganic materials. This type of analysis is recorded in the form of a range, in which each region corresponds to a specific molecular vibration. A Raman spectrum offers distinguishable band areas proportional to concentration, and the entire spectrum is a fingerprint of the characteristic found in the sample being tested.
The interpretation of the spectrum, and the resulting identification of the components found, is based on a comparison of the unknown (test sample) with various spectra of known substances that have already been analyzed.
Analysis by X-ray diffraction (X-Ray Diffraction, XRD)
The X-ray diffractometer (XRD) is an invasive and non-destructive technique, which is very popular for analyzinf the identity of colorants, rocks, inorganic ground materials, metal. It gives information on the three dimensional arrangement of atoms or molecules in a crystalline material, and measures the shape and crystal size of a material used in an artwork.