Low Frequency Dynamics in Water and Aqueous Solutions of ZnCl sub 2 : A Comparative Investigation by Raman, Rayleigh Wing and Inelastic Neutron Scattering

摘要

In this paper we report the results of a comprehensive investigation on the low ( omega < or approximately 400 cm exp -1 ) and very low (0.2 cm exp -1 < or approximately omega < or approximately 40 cm exp -1 ) frequency vibrational and structural dynamics in water and aqueous solutions of ZnCl sub 2 (for concentrations up to saturation). Time-of-flight inelastic neutron scattering and Raman spectroscopy were used to obtain the vibrational frequency distributions and the frequency dependence of the Raman electron vibration coupling function. Structural relaxation times were determined by depolarized Rayleigh wing scattering. The results, which confirm that these systems are best viewed as ''locally amorphous solids'', are discussed in terms of locally ordered, dynamically correlated patches in which structure and dynamics are strongly influenced by the solute, especially by its action on the water hydrogen bond. (ERA citation 10:028178)