Infrared Internal Reflection Spectra of Crystalline Quartz I. Hydroxyl Groups

Abstract

AbstractIn the O ‐ H‐stretching region three sharp symmetrical absorption bands at 3689 ± 1, 3650 ± 1, and 3620 ± 1 cm−1 and a broad band at 3410 cm−1 are observed on ground α‐quartz by Internal Reflection Spectroscopy (IRS). The bands at 3689 and 3620 cm−1 are correlated to two types of free surface hydroxyl groups, at 3650 cm−1 to isolated adsorbed water molecules and at 3410 cm−1 to liquid or hydrogen bonded water.Vacuum treatment at different temperatures (50 ‐ 250°C), examination of the region of deformation vibrations and isotopic exchange with heavy water confirmed these assignments. From the results it is concluded that the surface of crystalline α‐quartz seems to be more like γ‐Al2O3 than it is like amorphous SiO2, because two spectroscopically distinct types of free hydroxyl groups are observed.