title: Water Dynamics from THz Spectroscopy Reveal the Locus of a Liquid-Liquid Binodal Limit in Aqueous CaCO3Solutions.
abstract: Many phenomena depend on CaCO3nucleation where the role of water remains enigmatic. Changes in THz absorption during the early stages of CaCO3nucleation evidence altered coupled motions of hydrated calcium and carbonate ions. The direct link between these changes and the continuous development of the ion activity product reveals the locus of a liquid-liquid binodal limit. The data strongly suggest that proto-structured amorphous CaCO3forms through solidification of initially liquid precursors. Furthermore, polycarboxylates, which stabilize liquid precursors of CaCO3, significantly enhance the kinetic stability of the metastable liquid-liquid state, but they do not affect the locus of the binodal limit. The importance of water network dynamics in phase separation mechanisms can be understood based on the notions of the pre-nucleation cluster pathway, and is likely to be more general for aqueous systems.
authors.affiliation: Lehrstuhl für Physikalische Chemie 2, Ruhr-Universität Bochum, Universitätsstrasse 150, 44801, Bochum, Germany.
authors.forename: Federico
authors.initials: F
authors.lastname: Sebastiani
authors.affiliation: Physical Chemistry, University of Konstanz, Universitätsstrasse 10, 78457, Konstanz, Germany.
authors.forename: Stefan L P
authors.initials: SL
authors.lastname: Wolf
authors.affiliation: Department of Biological Regulation, The Weizmann Institute of Science, 234 Herzl St., Rehovot, 7610001, Israel.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Born
authors.affiliation: Lehrstuhl für Physikalische Chemie 2, Ruhr-Universität Bochum, Universitätsstrasse 150, 44801, Bochum, Germany.
authors.forename: Trung Quan
authors.initials: TQ
authors.lastname: Luong
authors.affiliation: Physical Chemistry, University of Konstanz, Universitätsstrasse 10, 78457, Konstanz, Germany.
authors.forename: Helmut
authors.initials: H
authors.lastname: Cölfen
authors.affiliation: Physical Chemistry, University of Konstanz, Universitätsstrasse 10, 78457, Konstanz, Germany.
authors.forename: Denis
authors.initials: D
authors.lastname: Gebauer
authors.affiliation: Lehrstuhl für Physikalische Chemie 2, Ruhr-Universität Bochum, Universitätsstrasse 150, 44801, Bochum, Germany.
authors.forename: Martina
authors.initials: M
authors.lastname: Havenith
keywords: THz spectroscopy; calcium carbonate; phase diagrams; pre-nucleation clusters; water chemistry