Relaxation process in deeply supercooled water by Mandelstam-Brillouin scattering

Magazù, Salvatore; Maisano, G.; Majolino, D.; Mallamace, Francesco; Migliardo, P.; Aliotta, F.; Vasi, C.

doi:10.1021/j100339a077

Cited by 48 publications

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“…We thus observe both an "ordinary" sound velocity and a relaxed high-frequency mode, which is present when Q > 1 nm −1 and propagates with a velocity close to that in amorphous ice (∼3,200 m/s) (18). This sound dispersion-observed using light scattering in the supercooled phase and inelastic X-ray scattering (IXS) in the high-frequency regime [ω/2π ∼ 10 13 Hz (19)] inside the stable phase (260 < T < 370 K)-is due to structural relaxation, as proposed by a molecular dynamics (MD) simulation study (20).…”

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confidence: 78%

“…Within the framework of extended MCT such a temperature represents the crossover to a water dynamics driven by hopping processes among clusters with a characteristic length proportional to ξ. The v(T) data measured using the BS (18,32) and IUVS (full symbols) (33) techniques at different wave vectors (Q). At the top are the v hf (T) data obtained using IXS (19,34) and IUVS.…”

Section: T(k)mentioning

confidence: 99%

“…Scattering experiments on bulk water, from the stable to the supercooled phase (14,18,(21)(22)(23)(24), indicate a strong dispersion, v = v(Q, ω), that on the basis of the previous equations is linked to the compressibilities.…”

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confidence: 99%

“…In specific, we consider the velocity dispersion (18)(19)(20) asking to what extent is sound velocity in water v a function of the probe wave vector ðQÞ and the frequency (ω). Water structure has a viscoelastic behavior that is reflected in the scattered spectra and that persists under ambient conditions.…”

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confidence: 99%

“…In this conceptual framework, many studies have produced evidence for the existence of relaxing structures in the liquid, whose size increases as T decreases (14,18,(21)(22)(23)(24), and for their effects on the transport, configurational, and vibrational properties of the system. In the time domain, as T decreases the HB average relaxation time (〈τ〉) strongly increases (up to many orders of magnitude), and the parallel frequency domain is characterized by viscoelasticity and strong dispersions in sound propagation (9,18,19).…”

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confidence: 99%

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Possible relation of water structural relaxation to water anomalies

Mallamace

Corsaro

Stanley

2013

Proc. Natl. Acad. Sci. U.S.A.

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The anomalous behavior of thermodynamic response functions is an unsolved problem in the physics of water. The mechanism that gives rise to the dramatic indefinite increase at low temperature in the heat capacity, the compressibility, and the coefficient of thermal expansion, is unknown. We explore this problem by analyzing both new and existing experimental data on the power spectrum S(Q, ω) of bulk and confined water at ambient pressure. When decreasing the temperature, we find that the liquid undergoes a structural transformation coinciding with the onset of an extended hydrogen bond network. This network onset seems to give rise to the marked viscoelastic behavior, consistent with the interesting possibility that the sound velocity and response functions of water depend upon both the frequency and wave vector.A lthough water is one of the simplest molecules, it is in reality a very complex liquid displaying more than 64 counterintuitive anomalies, most of which have not been adequately explained (1, 2). The best known of these is its density behavior: unlike most liquids, water displays a maximum at 4°C, and becomes less dense rather than more dense when it freezes. Other unexplained anomalies occur for response functions such as the isothermal compressibility K T , the isobaric heat capacity C P , and the thermal expansion coefficient α P . Moreover, if one extrapolates these functions into the metastable supercooled phase of water below the melting temperature (T M = 273 K at atmospheric pressure), and above the homogeneous nucleation temperature (T H ∼ 231 K), they behave as if they might diverge at a singular temperature T S ∼ 228 K (1). Water is a glassy liquid below the glass transition temperature T g ∼ 130 K (2). Immediately above T g it transforms into a highly viscous fluid and ultimately crystallizes at T X ∼ 150 K. The region between T X and T H is a "no-man's land" within which bulk liquid water cannot be studied (1). For these and other reasons, liquid water is one of the most exciting research topics, and an enormous number of studies have sought to elucidate the physical reasons for water's unusual properties.There are four current hypotheses (1), two of which have gained considerable attention: the singularity-free hypothesis (3, 4) and the liquid-liquid critical point (LLCP) hypothesis (5). The LLCP hypothesis is based on two assumptions: (i) that water displays the phenomenon of "liquid polymorphism" (6) and (ii) as T decreases, the hydrogen bonds (HBs) begin to form an open tetrahedrally coordinated HB network. If we begin with the stable liquid phase and decrease T, the HB lifetime and the cluster stability increase, and this altered local structure continues through the no-man's land down to the amorphous phase region. Amorphous solid water is widely believed to display polymorphism: below T g , low-density amorphous (LDA) and high-density amorphous (HDA) structures (7) can be transformed from one to the other by tuning the pressure. Hence liquid water may have local structural features...

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confidence: 78%

Section: T(k)mentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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confidence: 99%

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Possible relation of water structural relaxation to water anomalies

Mallamace

Corsaro

Stanley

2013

Proc. Natl. Acad. Sci. U.S.A.

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Experimental tests for a liquid-liquid critical point in water

Mallamace

Corsaro

Mallamace

et al. 2020

Sci. China Phys. Mech. Astron.

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Water is a fascinating material. Its composition is simple-one oxygen and two hydrogen atoms-but its chemistry and physics are extremely complex and exhibit 75 documented anomalies. Although these anomalies and their molecular origin are not completely understood, we know that hydrogen bonds play key roles in all of the phases of water. Moreover, there is experimental evidence that the polymorphism of the ice structure extends into the liquid phase and is associated with a liquid-liquid coexistence line. This is currently a topic of great interest in water research because there are indications that the end point of the coexistence line corresponds to a second critical point inside the supercooled liquid regime. We examine the recent progress in understanding water anomalies and the liquid-liquid phase transition hypothesis, including the results of recent experimental work and molecular simulations of both bulk and confined water. We examine experimental results that test whether the behavior of liquid water is consistent with the "liquid polymorphism" hypothesis that liquid water can exist in two distinct phases of differing densities. We also examine recent research on the anomalies of nanoconfined water and, in particular, on water in biological environments. We find that the concept of liquid polymorphism can also describe the properties of other liquids that have two characteristic length scales. hydrophobic-hydrophilic interactions, water systems, thermal properties

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Dynamical states in liquid water

Aliotta

Maisano

1993

Journal of Molecular Liquids

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Relaxation process in deeply supercooled water by Mandelstam-Brillouin scattering

Cited by 48 publications

References 0 publications

Possible relation of water structural relaxation to water anomalies

Possible relation of water structural relaxation to water anomalies

Experimental tests for a liquid-liquid critical point in water

Dynamical states in liquid water

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