Size Dependent Ultrafast Cooling of Water Droplets in Microemulsions by Picosecond Infrared Spectroscopy

Seifert, G.; Patzlaff, T.; Graener, H.

doi:10.1103/physrevlett.88.147402

Cited by 54 publications

(73 citation statements)

References 22 publications

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“…The experimental data, including the most peculiar features, are excellently reproduced by a simple phenomenological model in which a monodisperse distribution of liquid spherical particles grows, rearranges during coalescence, and decreases its volume when the temperature reaches again the melting temperature. Despite the strong approximations used (nucleation law, shape and size homogeneity) we are able to provide a precise time evolution of the droplets' dimensions that nicely connects the previous knowledge of the initial 250 ps (9,13,16,27) to the macroscopic domain. The melting implies the relaxation of the superheated lattice at ice/water interfaces.…”

Section: (T) Average Diameter D(t) and Concentration C(t) Of The Drmentioning

confidence: 93%

Melting dynamics of ice in the mesoscopic regime

Citroni

Fanetti

Falsini³

et al. 2017

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

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How does a crystal melt? How long does it take for melt nuclei to grow? The melting mechanisms have been addressed by several theoretical and experimental works, covering a subnanosecond time window with sample sizes of tens of nanometers and thus suitable to determine the onset of the process but unable to unveil the following dynamics. On the other hand, macroscopic observations of phase transitions, with millisecond or longer time resolution, account for processes occurring at surfaces and time limited by thermal contact with the environment. Here, we fill the gap between these two extremes, investigating the melting of ice in the entire mesoscopic regime. A bulk ice I h or ice VI sample is homogeneously heated by a picosecond infrared pulse, which delivers all of the energy necessary for complete melting. The evolution of melt/ice interfaces thereafter is monitored by Mie scattering with nanosecond resolution, for all of the time needed for the sample to reequilibrate. The growth of the liquid domains, over distances of micrometers, takes hundreds of nanoseconds, a time orders of magnitude larger than expected from simple H-bond dynamics.Mie scattering | temperature jump | superheating | laser heating | anvil cell M elting of ice is one of the most common occurrences on our planet, from polar ices to glaciers, to the morning frost and the preparation of our drinks. Ices are present as well in extraterrestrial environments, planetary and intersellar, going through extremely different pressure and temperature conditions, where many phase boundaries are encountered. The molecular mechanisms of melting and the characteristic timescales of the process are not well elucidated, as for any other phase transition. In fact, great effort is presently being made with state of the art experimental techniques to understand the intrinsic kinetics of structural transformations, particularly under dynamic compression, by which phase-transition boundaries up to extreme pressures (P) and temperatures (T) can be accessed (1-6). Melting is the least hindered of phase transitions, requiring the disruption of the crystalline order and the achievement of the local structure of the liquid phase.The dynamics of melting have been studied up to the present in the picosecond timescale, observing structural changes on a length scale of few nanometers, in the attempt to explain the fundamental mechanisms of the transition onset. In both simulations and experiments, micrometric-or submicrometric-sized crystals can be rapidly heated above the melting temperature (Tm ), into a superheated state where melting occurs. Metals and water ice have been the test systems. Simulations have revealed a nucleation and growth mechanism (7-11), and nucleation has been especially addressed, in trying to determine the minimum number of atoms/molecules needed to form a critical nucleus for the transitions, the solid/melt interfacial energy, the transient local structures achieved during the transformation, and the role of defects and surfaces. Experimentally...

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Section: (T) Average Diameter D(t) and Concentration C(t) Of The Drmentioning

confidence: 93%

Melting dynamics of ice in the mesoscopic regime

Citroni

Fanetti

Falsini³

et al. 2017

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

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“…Because the heat is not homogeneously distributed within the sample, the micelles will cool to the surrounding solvent on a picosecond timescale. 24 When the micelle cooling is complete, the heat is equilibrated over the micelles and the solvent. Since the solvent takes up the majority of the sample volume, the final heating effect on the micelles will be very small.…”

Section: A Ultrafast Heating Dynamics and Micelle Stabilitymentioning

confidence: 99%

“…We used the anionic lipid surfactant sodium bis͑2-ethylhexyl͒ sulfosuccinate ͑AOT͒, which is known to form reverse micelles that are reasonably monodisperse at room temperature ͓ϳ15% size polydispersity ͑standard deviation size/mean size͔͒. 23,24 The size of the water droplets can be easily varied by changing the molar water-to-AOT ratio, conventionally denoted by the parameter w 0 = ͓water͔ / ͓AOT͔.…”

Section: A Sample Preparationmentioning

confidence: 99%

Vibrational dynamics of ice in reverse micelles

Dokter

Petersen

Woutersen

et al. 2008

The Journal of Chemical Physics

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The ultrafast vibrational dynamics of HDO : D 2 O ice at 180 K in anionic reverse micelles is studied by midinfrared femtosecond pump-probe spectroscopy. Solutions containing reverse micelles are cooled to low temperatures by a fast-freezing procedure. The heating dynamics of the micellar solutions is studied to characterize the micellar structure. Small reverse micelles with a water content up to approximately 150 water molecules contain an amorphous form of ice that shows remarkably different vibrational dynamics compared to bulk hexagonal ice. The micellar amorphous ice has a much longer vibrational lifetime than bulk hexagonal ice and micellar liquid water. The vibrational lifetime is observed to increase linearly from 0.7 to 4 ps with the resonance frequency ranging from 3100 to 3500 cm −1 . From the pump dependence of the vibrational relaxation the homogeneous linewidth of the amorphous ice is determined ͑55Ϯ 5 cm −1 ͒.

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“…One direction that has been conventionally pursued is the removal of the complications related to the intra-and intermolecular couplings between the OH oscillators by substitution H 2 O with its deuterated isotope HDO. [11][12][13]16 Another possibility, which also mimics biological situations, 17 is to alter the complexity of the hydrogen bond network by studying water at interfaces, 18,19 in reverse micelles, [20][21][22][23][24][25][26][27] or in mixtures with various solvents. 11,28,29 The last setting is particularly advantageous because it allows investigating spatially separated water molecules and, thus, provides a unique opportunity to study purely intramolecular properties, which are not screened by interactions with other water molecules.…”

Section: Introductionmentioning

confidence: 99%

Ultrafast anisotropy dynamics of water molecules dissolved in acetonitrile

Cringus

Jansen

Pshenichnikov

et al. 2007

The Journal of Chemical Physics

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Infrared pump-probe experiments are performed on isolated H 2 O molecules diluted in acetonitrile in the spectral region of the OH stretching vibration. The large separation between water molecules excludes intermolecular interactions, while acetonitrile as a solvent provides substantial hydrogen bonding. Intramolecular coupling between symmetric and asymmetric modes results in the anisotropy decay to the frequency-dependent values of ϳ0 -0.2 with a 0.2 ps time constant. The experimental data are consistent with a theoretical model that includes intramolecular coupling, anharmonicity, and environmental fluctuations. Our results demonstrate that intramolecular processes are essential for the H 2 O stretching mode relaxation and therefore can compete with the intermolecular energy transfer in bulk water.

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Size Dependent Ultrafast Cooling of Water Droplets in Microemulsions by Picosecond Infrared Spectroscopy

Cited by 54 publications

References 22 publications

Melting dynamics of ice in the mesoscopic regime

Melting dynamics of ice in the mesoscopic regime

Vibrational dynamics of ice in reverse micelles

Ultrafast anisotropy dynamics of water molecules dissolved in acetonitrile

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