Preparation and spectroscopic study (UV-visible, NRI) study of tin dioxide

High surface area tin dioxide has been prepared and studied by different me thods: UV-vis-NIR diffuse reflectance, transmission infrared spectroscopy, electron microscopy. Treatments in reducing atmospheres (vacuo, hydrazine) give rise to a broad absorption in the visible range, apart from the interb and transition of SnO2 which appears near 330 nm (3,8 eV). Upon heating in oxygen, this broad absorption disappears, which indicates that the stoichio metry is restored. The near IR range shows harmonics and combinations of OH and Sn-O-Sn groups while mid-IR spectra recorded in controlled atmosphere show various bands ascribed to these groups; these results are discussed in relation with previous and sometimes contradictory results of the literatu re.