Laser Raman Spectral Determination of Zinc Halide Complexes in Aqueous Solutions as a Function of Temperature and Pressure

Abstract

Laser Raman spectroscopy has been used to determine directly the aqueous-phase zinc chloride and bromide species in solution as a function of temperature and pressure. With the use of the bromide system as a model, and by adjustment of the chemical and physical conditions to promote changes in the chemical equilibrium, identification of the mono-, di-, tri-, and tetra-halo zinc complexes has been performed. The spectral band positions, the Raman scattering coefficients, and the relative concentrations of the complexes are reported. The temperature and pressure dependence on the relative concentrations of the complexes have been examined. For the zinc/halide aqueous systems, temperature has a much more pronounced effect upon the species distributions than does pressure.