Hydration dynamics in CaCO 3 nucleation by THz spectroscopy

In CaCO 3 nucleation, the role of water remains enigmatic. Changes in THz absorption during the early stages of CaCO 3 nucleation evidence altered coupled motions of hydrated calcium and carbonate ions. By high precision THz absorption measurements we were able to follow the changes in the hydration bond dynamics during nucleation. Our THz data strongly suggest that amorphous CaCO 3 forms through solidification of initially liquid precursors. Polycarboxylates, which stabilize CaCO 3 liquid precursors, significantly enhance the kinetic stability of the metastable liquid-liquid state. The importance of water network dynamics in phase separation mechanisms as tested by THz absorption measurements using a p-Ge spectrometer is likely to be more general for aqueous systems.