Shrinking of Rapidly Evaporating Water Microdroplets Reveals their Extreme Supercooling

• Published in: Physical review letters Vol. 120; no. 1; p. 015501
• Main Authors: Goy, Claudia, Potenza, Marco A C, Dedera, Sebastian, Tomut, Marilena, Guillerm, Emmanuel, Kalinin, Anton, Voss, Kay-Obbe, Schottelius, Alexander, Petridis, Nikolaos, Prosvetov, Alexey, Tejeda, Guzmán, Fernández, José M, Trautmann, Christina, Caupin, Frédéric, Glasmacher, Ulrich, Grisenti, Robert E
• Format: Journal Article
• Language: English
• Published: United States American Physical Society 05-01-2018
• Subjects: Chemical Sciences; Engineering Sciences; Physics; Temperature; Liquids; Sample preparation; Raman spectroscopy; Light scattering; Structural properties
• ISSN: 0031-9007; 1079-7114
• DOI: 10.1103/PhysRevLett.120.015501

The fast evaporative cooling of micrometer-sized water droplets in a vacuum offers the appealing possibility to investigate supercooled water-below the melting point but still a liquid-at temperatures far beyond the state of the art. However, it is challenging to obtain a reliable value of the droplet temperature under such extreme experimental conditions. Here, the observation of morphology-dependent resonances in the Raman scattering from a train of perfectly uniform water droplets allows us to measure the variation in droplet size resulting from evaporative mass losses with an absolute precision of better than 0.2%. This finding proves crucial to an unambiguous determination of the droplet temperature. In particular, we find that a fraction of water droplets with an initial diameter of 6379±12  nm remain liquid down to 230.6±0.6  K. Our results question temperature estimates reported recently for larger supercooled water droplets and provide valuable information on the hydrogen-bond network in liquid water in the hard-to-access deeply supercooled regime.