Fourier-transform infrared photo-acoustic spectroscopy study of the free hydroxyl group vibration. Dependence on the pretreatment temperature

Abstract

The fundamental free hydroxyl group vibration of silica gel has been studied using high-resolution Fourier-transform infrared photo-acoustic spectroscopy (FTIR-PAS). The position of the absorption maximum shifts according to the pretreatment temperature of the silica gel. The hydroxylic environment of the free hydroxyl group probably influences the peak position. This was modelled to estimate the relative surface coverages of the free and bridged hydroxyl groups.