Advantages of the use of SR-FT-IR microspectroscopy: applications to cultural heritage.

Synchrotron radiation Fourier transform infrared (SR-FT-IR) microspectroscopy represents an advance over conventional FT-IR spectroscopy because it gives a higher signal/noise ratio at the highest spatial resolution due to the high brightness and collimation of synchrotron radiation. It has been successfully applied to the study of ancient paintings, alteration and corrosion layers which are heterogeneous microlayered materials made by complex mixtures of organic and inorganic compounds. Moreover, the high brightness attribute allows FT-IR spectra to be routinely obtained directly on the surfaces of the objects and opens the possibility for nondestructive testing of museum objects. We present in this paper a selection of applications of SR-FT-IR to the analysis of ancient paintings, alteration and corrosion layers where the technique has proven to be especially useful: first, the separation and identification of pigment microparticles from ancient Roman wall paintings; second, the determination of the binding media and the byproducts resulting from the interaction between binders and pigments from medieval altarpieces; and third, the study of the surface corrosion layers of a bronze helmet by means of direct analysis of the surface.