Infrared Spectra of a Water‐Containing Glass

Infrared absorption was measured on an NajO‐K 2 O‐ZnO‐Al 2 O 3 ‐SiO 2 glass with up to ∼11 wt% water. Fundamental and overtone‐combination bands were observed at 1.41, 1.91, 2.22, 2.87, and 6.1 μm. Molar absorptivities were determined for the hydrated glass for H 2 O and OH levels using the molar absorptivity calculated for the 2.22‐μm band in the as‐melted glass. By this procedure the concentration of molecular water and OH groups could be determined separately. These results show that the OH content of the hydrated glass, as determined from the 2.22‐μm band, is constant at >7 wt% H 2 O; additional H 2 O is attributed to molecular water only. Good agreement was found between these data and H 2 O/OH molecular ratios obtained from NMR.