Absorption of Infrared Radiation by D2O and HDO Mixed with Montmorillonite1

J. Sallé de Chou, P. F. Low and C. B. Roth
Department of Agronomy, Purdue University West Lafayette, Indiana 47907
1Journal Paper No. 7591, Purdue University Agricultural Experiment Station.

Abstract: The frequency, ν, for O-D stretching in D2O films between the superimposed layers of different micas and montmorillonites was measured at several film thicknesses and temperatures of 2° and 25°C by infrared spectroscopy. The molar absorptivity, ε, for O-D stretching in HDO films between the montmorillonite layers was also measured at different film thicknesses and 25°C. It was found that ν is related to mw/mm, the mass ratio of D2O to mica or montmorillonite, by the equation ν = ν0 exp β/(mw/mm) where ν0 is the O-D stretching frequency in pure D2O and β is a constant. Since mw/mm is proportional to a, the area under the absorption peak, mw/mm can be replaced by a in this equation. It was also found that ε decreased dramatically as the thickness of the water film between the montmorillonite layers decreased. These results were interpreted to mean that the structure of the interlayer water is perturbed by the interlayer cations and/or silicate surfaces.

Key Words: Absorption • Deuterium • Infrared • Molar absorptivity • Montmorillonite • Water

Clays and Clay Minerals; April 1980 v. 28; no. 2; p. 111-118; DOI: 10.1346/CCMN.1980.0280206
© 1980, The Clay Minerals Society
Clay Minerals Society (www.clays.org)