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Exploration of the phase diagram of liquid water in the metastable region by means of synthetic fluid inclusions

English title Exploration of the phase diagram of liquid water in the metastable region by means of synthetic fluid inclusions
Applicant Frenz Martin
Number 159542
Funding scheme Project funding (Div. I-III)
Research institution Institut für angewandte Physik Universität Bern
Institution of higher education University of Berne - BE
Main discipline Condensed Matter Physics
Start/End 01.04.2015 - 28.02.2017
Approved amount 133'525.00
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All Disciplines (2)

Discipline
Condensed Matter Physics
Other disciplines of Physics

Keywords (7)

phase nucleation; femtosecond laser; fluid inclusions; microthermometry; Brillouin scattering; Raman scattering; metastable water

Lay Summary (German)

Lead
Obwohl Wasser zweifelsohne eines der wichtigsten Elemente auf unserer Erde ist, sind dessen Eigenschaften noch nicht alle erforscht. Dies hängt daran, dass einige Bereiche im Phasendiagramm von Wasser bisher experimentell nicht zugängig waren. Vor allem der Verlauf der Spinodalen im Bereich hoher negativer Drücke löst Kontroversen aus. Durch den Einsatz von synthetischen Flüssigkeitseinschlüssen in Quarz sind diese, für das Verständnis von Wasser wichtige Bereiche nun experimentell zugänglich.
Lay summary

Inhalt und Ziel des Forschungsprojekts

Das Ziel unseres Forschungsprojekts ist es, den gesamten Bereich des Phasendiagramms von reinem Wasser experimentell zu studieren. Dies ist möglich indem wir synthetische Flüssigkeitseinschlüsse, von denen wir die Eigenschaften sehr genau kennen, mit Hilfe der sehr empfindlichen und hochauflösenden Raman- und Brillouinmikroskopie untersuchen. Damit wir den metastabilen Bereich untersuchen können, benötigen wir synthetische Einschlüsse mit Dichten zwischen 0.9997 und 0.9348 g/cm3. Da Einschlüsse dieser hohen Dichte im Normalfall während des Abkühlens keine spontane Nukleation einer Dampfblase zeigen, soll diese Nukleation mit Hilfe eines ultrakurzen Laserpulses erzwungen werden. Mikrothermometriemessungen der prograden und retrograden Homogenisierungstemperatur, der Eisnukleation- und Eisschmelztemperatur unter hohem negativem Druck erlauben es uns, den Verlauf der Spinodalen zu bestimmen.

Wissenschaftlicher und gesellschaftlicher Kontext des Forschungsprojekts

Unser Forschungsprojekt soll dazu beitragen, fundamentale Eigenschaften von Wasser besser zu verstehen. Dieses Wissen ist aber auch von praktischem Nutzen zum Beispiel bei der Untersuchung von Flüssigkeitseinschlüssen in Stalagmiten, die zur Bestimmung von Paleotemperaturen verwendet werden können, da sie ein natürliches Klimaarchiv darstellen.

Direct link to Lay Summary Last update: 06.05.2015

Responsible applicant and co-applicants

Employees

Name Institute

Publications

Publication
Comment on “Maxima in the thermodynamic response and correlation functions of deeply supercooled water”
Caupin Frédéric, Holten Vincent, Qiu Chen, Guillerm Emmanuel, Wilke Max, Frenz Martin, Teixeira José, Soper Alan K. (2018), Comment on “Maxima in the thermodynamic response and correlation functions of deeply supercooled water”, in Science, 360(6390), eaat1634-eaat1634.
Exploration of the phase diagram of liquid water in the low-temperature metastable region using synthetic fluid inclusions
Qiu C., Krüger Y., Wilke M., Marti D., Rička J., Frenz M. (2016), Exploration of the phase diagram of liquid water in the low-temperature metastable region using synthetic fluid inclusions, in Phys. Chem. Chem. Phys., 18(40), 28227-28241.
Microthermometric data of stretched and super-cooled liquid water obtained from high-density synthetic fluid inclusions
Qui Chen, Krüger Yves, Wilke Max, Marti Dominik, Rička Jaro, Frenz Martin, Microthermometric data of stretched and super-cooled liquid water obtained from high-density synthetic fluid inclusions, in The Sorby Conference on Fluid and Melt Inclusions, ECROFI XXIII, LeedsECROFI, Leeds.

Collaboration

Group / person Country
Types of collaboration
Dr. Max Wilke, Deutsches GeoForschungsZentrum GFZ, Potsdam Germany (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Research Infrastructure
Université Claude Bernard Lyon 1 France (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
- Exchange of personnel
Dr. A. Murk, Microwave department, Institute of Applied Physics,University Bern Switzerland (Europe)
- Research Infrastructure

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
Seminar at Institute of Light and Matter, Université Claude Bernard Lyon 1 Individual talk Liquid water in no man’s land–phase transition of water under negative pressure 23.05.2016 Lyon, France Krüger Yves; Qiu Chen; Frenz Martin; Ricka Jaroslav;
The Sorby Conference on Fluid and Melt Inclusions, ECROFI XXIII Talk given at a conference Microthermometric data of stretched and super-cooled liquid water obtained from high-density synthetic fluid inclusions 29.06.2015 Leeds, Great Britain and Northern Ireland Frenz Martin; Qiu Chen; Ricka Jaroslav; Krüger Yves;


Associated projects

Number Title Start Funding scheme
140777 Exploration of the phase diagram of liquid water in the metastable region by means of synthetic fluid inclusions 01.03.2013 Project funding (Div. I-III)
147674 STALCLIM II - Multi-proxy climatic and environmental reconstructions from stalagmites from Switzerland, Turkey, Arabia and India 01.01.2014 Sinergia

Abstract

Our research is aimed at the fundamental understanding of the remarkable thermodynamic properties of water. Specifically, we are interested in the purely understood low temperature metastable region. The metastable state of liquid water spans a wide range of p-T conditions between the liquid-vapour equilibrium curve and the liquid spinodal, i.e., the stability limit of the metastable liquid state. The spinodal curve starts at the critical point and runs to negative pressures with decreasing temperature. At low temperatures, however, the shape of the spinodal curve is controversial and different theoretical models have been discussed in the literature. One of them is the “Stability Limit Conjecture” proposed by Speedy (1982), a thermodynamic model that postulates a single continuous stability limit (spinodal) for both, the superheated and the super cooled states of liquid water. The model assumes that the TMD line (Temperature of Maximum Density) remains negatively sloped in the metastable region and intersects the spinodal. As a consequence of this, the spinodal must pass through a pressure minimum at the intersection with the TMD line and returns to positive pressures at low temperatures. Interestingly, the extrapolation of the IAPWS-95 formulation of the PVT surface of liquid water into the metastable region displays a similar behaviour, namely a negatively sloped TMD line and a spinodal curve that passes through a pressure minimum and bends towards positive pressures at low temperatures. In contrast to the thermodynamic model proposed by Speedy, molecular dynamics simulations by Poole et al. indicate that the TMD line bends to a positive slope in the metastable region and does not intersect the spinodal curve. Consequently, the spinodal remains positively sloped at low temperatures and does not bend towards positive pressures. Up to now, all predictions about the shape of the TMD line are purely based on theoretical considerations and not yet experimentally verified.To shed light on this controversial issue, we pursue an experimental approach using synthetic pure water inclusions in quartz as microscopic sample cells capable of withstanding the large negative pressure needed to follow the trend of the TMD line and the shape of the spinodal curve. In inclusions, negative pressures of down to -1.4 kbar can be achieved by isochoric cooling. In contrast to previous experimental studies we will consider both, the prograde (upon heating) and the retrograde (upon cooling) homogenisation temperatures Th and Thr, respectively, as well as ice nucleation and ice melting temperatures at negative pressures. Therefore we need fluid inclusions that cover a range of homogenisation temperatures Th from 10 to 130°C, which corresponds to fluid densities between 0.9997 and 0.9348 g/cm3. In these high-density fluid inclusions, however, spontaneous nucleation of the vapour bubble usually fails to occur upon cooling below Th and therefore, we use single ultra-short laser pulses to induce bubble nucleation for subsequent Th measurements (Krüger et al., 2007). To assess the thermodynamic state of the inclusion-confined water in the necessary detail, we equipped our nucleation/homogenisation facility with the optical hardware for confocal micro-volume spectroscopy, including both, Raman and Brillouin scattering. Raman spectroscopy is used in the first place to identify the nucleation of ice, which is not visible from microscopic observations in metastable pure water inclusions, and to detect the presence of impurities. However, currently we are also evaluating the possibility to localize the pressure minima of the isochores by monitoring pressure-dependent changes of the Raman spectrum of water. It will be interesting to compare the Raman data with the complementary information obtained by the Brillouin technique. Brillouin spectroscopy measures the changes of the sound velocity, giving thus access to the adiabatic compressibility as an indicator of pressure changes. Maintaining and measuring negative pressures of the metastable water requires very small sample volumes, as are best preserved in small size inclusions. Therefore we are optimizing the spectroscopic techniques for best possible position resolution, as can be achieved by our confocal scheme utilizing the unique properties of single-mode optical fibres.In summary, using the combination of synthetic fluid inclusions of well-known properties and the high sensitive and high resolution Raman and Brillouin confocal microscopy setup offers for the first time experimental access to the entire phase diagram of pure water.
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