title: T dependence of vibrational dynamics of water in ion-exchanged zeolites A: a detailed Fourier transform infrared attenuated total reflection study.
abstract: In order to explore the influence of cation substitution on the vibrational dynamics of water molecules in zeolites, the evolution of structural properties of the O-H stretching band of water in fully hydrated Na-A and Mg-exchanged A zeolites has been studied, for different percentages of induced ion exchange, by Fourier transform infrared attenuated total reflection spectroscopy as a function of temperature. The differences revealed in the O-H stretching band shapes have been accounted by fitting the spectra as a sum of four components, corresponding to water molecules exhibiting different types of hydrogen bonding. The dependencies of the relative intensities, peak wave numbers, and bandwidths of the resolved components on temperature and Mg2+ content have been discussed. Evidence of the "structure-maker" role played by a zeolitic surface on physisorbed water, systematically enhanced by increasing the percentage of induced ion exchange, is given in the whole explored temperature range.
authors.affiliation: Department of Physics, University of Messina, Contrada Papardo, via Salita Sperone 31, P.O. Box 55, 98166 Sant' Agata, Messina, Italy.
authors.forename: Vincenza
authors.initials: V
authors.lastname: Crupi
authors.forename: Francesca
authors.initials: F
authors.lastname: Longo
authors.forename: Domenico
authors.initials: D
authors.lastname: Majolino
authors.forename: Valentina
authors.initials: V
authors.lastname: Venuti