An X-ray absorption spectroscopy study of the pressure and temperature dependence of ZnBr2 aqueous supercritical solutions

X-ray absorption spectroscopy (XAS) experiments have been performed on 1.0 and 1.6 M ZnBr2 aqueous solutions under ambient to supercritical conditions . Both the X-ray absorption near-edge structure (XANES) and the extended X- ray absorption fine structure (EXAFS) show striking evolutions, which indic ate major structural changes, with a strong reduction in hydration and the increasing formation of ZnBr pairs. A quantitative analysis of the evolutio n of the Zn environment is presented that supports the existence of a trans ition from an octahedral to a tetrahedral environment.