Dependence of water vibrational dynamics upon different confining matrices

Abstract

In the present work, we report a spectroscopic analysis of water confined in a powdered zeolite, Na A type, which is able to entrap 27 H₂O molecules, by Fourier transform infrared absorption, performed in the OH stretching region, 3000–3800 cm⁻¹. The investigation was carried out as a function of temperature and at different hydration levels. The spectroscopic results were interpreted in the framework of actual theories for associated liquids and on the basis of previously measurements performed in water confined in a different environment, a controlled silica glass (GelSil), by Raman scattering, always in the OH stretching region. The comparison between these two distinct cases of confinement condition unambiguously showed the role of structure maker played by the zeolite for confined water as opposed to the structure breaker character observed in the case of the GelSil matrix.