Characterization of Some Orange and Yellow Organic and Fluorescent Pigments by Raman Spectroscopy

Raman spectroscopy has become one of the most important vibrational analytical techniques for the investigation of paint samples and notably for organic pigments. For the analysis of modern materials, especially for synthetic inorganic and organic pigments the prospect of using Raman spectroscopy is an alternative to e.g. Py-GC-MS. It provides enough information allowing for a broad characterization of colourants either in raw samples, on cross-sections or insitu. One of the advantages of Raman spectroscopy over FTIR analysis is that it allows the detection of weak IR frequencies such as stretching vibrations of chemical groups, e.g. the nitro group in azo pigments, which represents the biggest family of organic pigments found in paintings.