Hydrogen bonded structure of water and aqueous solutions of sodium halides: a Raman spectroscopic study

The OH stretching (2500-4000 cm(-1)) Raman spectra from pure water and sodium halides solutions are obtained. The Raman contours are deconvoluted with five Gaussian components that their center frequencies are 3051, 3233, 3393, 3511 and 3628 cm(-1) respectively. From the Raman spectra and their deconvolutions similarities and differences of the effects of temperature and sodium halides on hydrogen bond structure of water are shown clearly. Like temperature, all of sodium halides break tetrahedral structure of water, and the Gaussian component of 3233 cm(-1) decreases and the components of 3393 and 3511 cm(-1) increase basically. The differences lie in their effects on the component 3051 and 3628 cm(-1). All of halogenic ions break tetrahedral structure of water and their breaking actions are in the order of F-1<Cl-1<Br-1<I-1. The reason is relative to the strength of halogenic ion-water and water-water hydrogen bonds. (C) 2004 Elsevier B.V. All rights reserved.