Spectra of Adsorbed Water and Surface Hydroxyl Groups on Nonacidic Oxides

Spectra of Adsorbed Water and Surface Hydroxyl Groups on Nonacidic Oxides 

The earliest observations of infrared bands due to hydroxyl groups on surfaces were made by workers who were primarily interested in the spectra of the solid rather than spectra of adsorbed molecules. Despite this difference in point of view, their interpretation of the hydroxyl bands is important to later studies of adsorption. 

Buswell and associates (34) studied the effect of variation in drying conditions on the spectrum of montmorillonite-water systems. The use of infrared to study the state of water in minerals had previously been suggested and briefly explored by Coblentz (35). The effect of drying on the 

The presence of two O—H stretching bands shows that there are at least two types of OH groups on the montmorillonite. Work which will be discussed later shows that interpretation of the spectra of the OH stretching bands is more complicated than would be expected. On the simplest basis the OH bands can be separated into those due to adsorbed water and those due to surface OH groups. These species can be distinguished in cases where it is possible to scan the spectral region past 6.2 p. Adsorbed water 

The species producing the 2.95-3.0-/ band in Fig. 16 can probably best be described as physically adsorbed water. The band at 2.75 n is due to surface OH groups of the type 

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