Investigation by infra-red spectroscopic methods of deuterium exchange properties of aerosil silicas

Abstract

The characteristics of the residual band at 3650 cm^–1 in the infra-red spectrum of deuterated aerosils have been determined. The band corresponds to hydroxyl groups and not to molecular water. It is assigned to interacting hydroxyls sited on neighbouring silicon atoms within the solid lattice of the silica particles. The effects of annealing the solid on the intensity of the residual band are described and a mechanism proposed for the removal of the corresponding species. The rehydration or chemisorption phenomena noted during adsorption and wetting studies performed at room temperatures are confined to the external surfaces of the solid.