The infrared transmission spectra of four silicate glasses before and after exposure to water

Abstract

The infrared transmission spectra of four silicate glasses were investigated. By using blown glass films, 1–2 μm thick, detailed infrared transmission spectra were generated over the 4000–180 cm⁻¹ range, both before and after the films were exposed to water. The water had little effect on the spectra of the 70SiO₂–20Na₂O–10Al₂O₃ (mol %) and Pyrex compositions, but had a large effect on the spectra of the 70SiO₂–30Na₂O (mol %) and Corning 015 compositions. The Si–O nonbridged stretching band at ∼950 cm⁻¹ and a largely overlooked bending band at ∼600 cm⁻¹ were the bands most sensitive to hydration in the 70/30 and 015 compositions. Changes were also seen in the Si–O–Si bridged stretching bands at ∼1050 cm⁻¹ and ∼770 cm⁻¹. The water, however, had no effect on the dominant Si–O–Si bending band at 460 cm⁻¹. It was also discovered that the 70/30 and 015 films reacted with the atmosphere to form a carbonate layer on their surface. This carbonate accounted for the 1450 cm⁻¹ and 230 cm⁻¹ bands seen in their infrared transmission spectra.