Identification of thin films on zinc substrates by FTIR and Raman spectroscopies

Raman and FTIR reflectance spectroscopies have been used for the characterization of the following zinc corrosion products formed by atmospheric corrosion : (ε-Zn(OH)2, hydrozincite Zn5(CO3)2(OH)6, simonkolleite Zn5Cl2(OH)8,H2O and zinc sulfates ZnSO4,H2O, Zn4SO4(OH)6, 5H2O and Zn4SO4(OH)6,H2O. The samples to analyze are either developed on metal or obtained by incrustation of submicronic particles of the compound on the surface on zinc substrates. Both the IR reflectance and Raman spectroscopies allow an easy identification of basic zinc salts : chloride by the Zn-O-H bending modes, carbonate and sulfates by the internal mode of the corresponding anion (ν3 region). A multianalytical approach combining FTIR reflectance spectroscopy, grazing incidence X-ray diffraction and SEM/EDS leads to different applications.