The low frequency dynamics of supercooled LiBr, 6H2O
Year: 2011
Authors: Bove L., Dreyfus C., Polian A., Bonello B., Malfanti I., Taschin A., Torre R., Pick R.M.
Autors Affiliation: Univ P&M Curie, IMPMC, Paris, France; CNRS, UMR 7590, Paris, France; Univ P&M Curie, INSP, Paris, France; CNRS, UMR 7588, Paris, France; Univ Florence, LENS, I-50121 Florence, Italy; Univ Florence, Dip Fis, I-50121 Florence, Italy.
Abstract: We present results of a series of experiments performed on LiBr, 6H(2)O from room temperature down to 172 K approximate to 1.2T(g). These ultrasound, Brillouin and depolarized light scattering, and transient grating experiments show that, above 215 K, this solution behaves like supercooled water: its zero frequency sound velocity C-0 continuously decreases with decreasing temperature, and the reorientational dynamics of the water molecules can be directly detected at some temperatures of this domain. Conversely, below 215 K, a new regime sets in, where the apparent C-0 is practically temperature independent and where a beta, Arrenhius like, relaxation process coexists with the usual, Vogel-Fulcher like, a relaxation process of the supercooled liquid. These results are similar to those recently obtained in LiCl, 6H(2)O. The onset of the new regime is possibly due to an increase of the interaction of the water molecules with a neighboring Li+ ion when lowering the temperature. We also compare our results with published dielectric data on water solutions of glass forming polyalcohols. Some of them present a low temperature splitting of their relaxation time similar to what is found in LiBr, 6H(2)O.
Journal/Review: JOURNAL OF CHEMICAL PHYSICS
Volume: 134 (3) Pages from: 34514-1 to: 34514-8
More Information: One of us (C.D.) is particularly thankful to Remi Marchal from ISO, Orsay, who was instrumental in collecting the US data. We also greatly acknowledge Pascal Munch’s help in the Brillouin and Raman low temperature measurements, and are grateful to Melanie Escudier and Michele Jacquet for the construction of our backscattering liquid cell. The Transient Grating experiments have been supported by the EC Grant No. RII3-CT-2003-506350. We would also like to acknowledge Dr. P. Bartolini’s continuous support during these experiments. Finally, we are very grateful to the (anonymous) referee who has pointed out to us the similarity of our results with those obtained in the polyalcohol-water mixtures.KeyWords: Longitudinal Acoustic Modes; Molecular Liquids Ii; Phenomenological Equations; Microscopic Derivation; Neutron-diffraction; Light-scattering; Water Mixtures; Glass; Crystallization; RelaxationDOI: 10.1063/1.3526939Citations: 10data from “WEB OF SCIENCE” (of Thomson Reuters) are update at: 2024-10-20References taken from IsiWeb of Knowledge: (subscribers only)