On 28.03.2011 Ivo Leito gave talk “ATR-FT-IR spectroscopy in the region of 550-230 cm^-1 for identification of inorganic pigments” at the the 241th ACS National Meeting, Spring 2011 in Anaheim (CA).

The presentation describes an analytical method for recording ATR-FT-IR spectra of inorganic pigments in the low wavenumber range (550-230 cm-1), which markedly extends the applicability of ATR-FT-IR spectroscpoy in identification of inorganic pigments that are important for the conservation of cultural heritage in different art objects.

The reference spectra presented in the talk (and many more) are available from the address http://tera.chem.ut.ee/IR_spectra/

Due to the nature of the ATR phenomenon poor-quality spectra are generally obtained from pure pigments, especially in the low wavenumber range. For obtaining good-quality spectra the pigments are mixed with linseed oil (in roughlt 1:1 ratio) and ATR-IR spectra are recorded from such mixtures. It is demonstrated on the example of 47 inorganic pigments widely used in historical paintings that this spectral range, essentially devoid of absorption peaks of the common binder materials, can be well used for identification of inorganic pigments in paint samples.

This developed approach markedly extends the possibilities of pigment identification/confirmation by ATR-IR spectroscopy. In some cases the method can be used alone for pigment identification and in many cases it provides useful additional evidence for pigment identification using other instrumental techniques. Several case studies of pigment identification of real paint samples using the developed method are presented.

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