title: Changing Hydrogen-Bond Structure during an Aqueous Liquid-Liquid Transition Investigated with Time-Resolved and Two-Dimensional Vibrational Spectroscopy.
abstract: We investigate the putative liquid-liquid phase transition in aqueous glycerol solution, using the OD-stretch mode in dilute OD/OH isotopic mixtures to probe the hydrogen-bond structure. The conversion exhibits Avrami kinetics with an exponent of n = 2.9 ± 0.1 (as opposed to n = 1.7 observed upon inducing ice nucleation and growth in the same sample), which indicates a transition from one liquid phase to another. Two-dimensional infrared (2D-IR) spectroscopy shows that the initial and final phases have different hydrogen-bond structures: the former has a single Gaussian distribution of hydrogen-bond lengths, whereas the latter has a bimodal distribution consisting of a broad distribution and a narrower, ice-like distribution. The 2D-IR spectrum of the final phase is identical to that of ice/glycerol at the same temperature. Combined with the kinetic data this suggests that the liquid-liquid transformation is immediately followed by a rapid formation of small (probably nanometer-sized) ice crystals.
authors.affiliation: Van 't Hoff Institute for Molecular Sciences (HIMS), University of Amsterdam , Science Park 904, 1098 XH Amsterdam, The Netherlands.
authors.forename: Jeroen R
authors.initials: JR
authors.lastname: Bruijn
authors.affiliation: Van 't Hoff Institute for Molecular Sciences (HIMS), University of Amsterdam , Science Park 904, 1098 XH Amsterdam, The Netherlands.
authors.forename: Tibert H
authors.initials: TH
authors.lastname: van der Loop
authors.affiliation: Van 't Hoff Institute for Molecular Sciences (HIMS), University of Amsterdam , Science Park 904, 1098 XH Amsterdam, The Netherlands.
authors.forename: Sander
authors.initials: S
authors.lastname: Woutersen