Study of the Structure of Quartz, Cristobalite, and Vitreous Silica by Reflection in Infrared

Abstract

Infrared spectra of α‐ and β‐quartz, α‐ and β‐cristobalite, and vitreous silica were studied by the reflection method using natural and polarized radiation in the 700 to 1400 cm⁻¹ wave number interval. By measuring the reflecting powers at two different angles of incidence, the indices of refraction and extinction were obtained and the absorption bands could be correctly located, sometimes at variance with the existing data, based on reflection maxima alone. The strong band at 1055 cm⁻¹ in α‐quartz and at 1095 cm⁻¹ in α‐cristobalite and vitreous silica can be assigned as a valence stretching $\mathrm{Si}{\displaystyle {lim}^{\leftarrow }}–\mathrm{O}{\displaystyle {lim}^{\to }}–\mathrm{Si}{\displaystyle {lim}^{\leftarrow }}$ vibration. Other observed bands are consistent with the already existing assignments. The effect of temperature on the total intensity and width of the bands was studied in a temperature interval between 4°K and 880°K.