PHOTOACOUSTIC FT-IR SPECTROSCOPY OF NATURAL COPPER PATINA

Fourier transform infrared photoacoustic spectroscopy (FT-IR PAS) has proved to be a useful tool for nondestructive testing of copper corros ion layer (patina) formed in the atmosphere. The samples cut from a pi ece of the roof of the Stockholm City Hall were examined without any a dditional pre-treatment. The components of the patina - brochantite Cu -4(OH)(6)SO4, antlerite Cu-3(OH)(4)SO4, basic cupric carbonate Cu2CO3( OH)(6)H2O as well as some other minerals were identified. The depth pr ofiling capability of FT-IR PAS was used to determine the degree of ph otoacoustic saturation of the spectral bands.