Far infrared and Raman spectroscopy analysis of inorganic pigments

Few research studies from the early seventies reported the use of far infrared (FIR) spectroscopy and its analytical potential. Especially in the field of cultural heritage, particular attention has not been given to this technique because of its destructive character; however, this can be overcome by employing Raman microscopy. Provided that enough quantity of the sample is available, FIR spectroscopy may represent a useful analytical method in the case of inorganic compounds that are not active in the mid infrared region and, because of the fluorescent effect produced by the organic media, not detectable even by Raman spectroscopy. In this article, the application of FIR spectroscopy has been applied for the characterisation of several inorganic pigments. A preparation method based on the use of polyethylene has been developed that allows analyses with moderate quantity of sample (0.5–1.5 mg). The data obtained have been compared with Raman results with the aim to build a common database. Some applications on real case studies are presented and discussed. Copyright © 2008 John Wiley & Sons, Ltd.