Water-related bands in the IR absorption spectra of silicate glasses

The IR absorption spectra of K 2O–CaO–BaO–SiO 2, Na 2O–SiO 2, and window glass samples at wavenumbers from 1200 to 10 000 cm −1 are investigated, depending on sample composition and prehistory, with the dispersion analysis method using the convolution model for the complex dielectric constant. In the 1500–3700 cm −1 region, the spectra are shown to contain 14–15 bands. Individual absorptivity maxima and the band frequencies and intensities are computed. The revision of common views on the total number and nature of the first order water-related bands in glass spectra started by the authors in their preceding papers is completed. Ten bands located throughout the 1500–3700 cm −1 region are shown to be due to the components of the stretching modes of the bound hydroxyl groups in three different structural sites. Four bands located within the 2850–3400 cm −1 region are confirmed to be due to the components of the asymmetric and symmetric stretching modes of the H 2O molecule. The 1674 cm −1 band found in the spectrum of a water-enriched sample only is assigned to the bending mode of the interstitial H 2O molecule. No less than 10 multiphonon water-related bands are shown to occur in the 3700–7500 cm −1 region. In the spectra of some samples, two other impurity bands around 1400 and 2600 cm −1 are found, these bands being assigned to the stretching mode of the interstitial carbonate ion and first overtone of this mode, respectively.