The formation of ice at the nanoscale is a challenging, basic scientific research question whose answer also has important implications for climate research and other fields.
The crystallization of ice from supercooled water is generally initiated by a process called nucleation. Because of the speed and size of nucleation—it occurs within nanoseconds and nanometers—probing it by experiment or simulation is a major challenge.
By using an advanced simulation method, Dr. Li and his collaborators, Davide Donadio of Germany’s Max Planck Institute for Polymer Research, and Giulia Galli, a professor of chemistry and physics at the University of California, Davis, were able to demonstrate that nucleation of ice is substantially suppressed in nano-sized water droplets. Their paper, “Ice nucleation at the nanoscale probes no man’s land of water,” was published today in the journal Nature Communications.
“A current challenge for scientists is to unveil water’s behaviors below -35 degrees Celsius and above -123 degrees Celsius, a temperature range that chemists call ‘no man’s land,’ ” said Dr. Li, a professor of civil and environmental engineering at the George Washington University School of Engineering and Applied Science. “Fast ice crystallization can hardly be avoided at such low temperatures, so maintaining water in a liquid state is a major experimental challenge.”
Since the frequency of ice nucleation scales with the volume of water, one of the strategies for overcoming this kinetic barrier is to reduce the volume of water. However, this raises the question of whether water at the nanoscale can still be regarded as equivalent to bulk water, and if not, where that boundary would be.
The team’s results answer this question. By showing that the ice nucleation rate at the nanoscale can be several orders of magnitude smaller than that of bulk water, they demonstrate that water at such a small scale can no longer be considered bulk water.
“We also predict where this boundary would reside at various temperatures,” Dr. Li said. The boundary refers to the size of the droplet where the difference vanishes. The team’s findings will help with the interpretation of molecular beam experiments and set the guidelines for experiments that probe the ‘no man’s land’ of water.
The results are also of importance in atmospheric science, as they may improve the climate model of the formation of ice clouds in upper troposphere, which effectively scatter incoming solar radiation and prevent earth from becoming overheated by the sun. The results have important implications in climate control research, too. One of the current debates is whether the formation of ice occurs near the surface or within the micrometer-sized droplets suspended in clouds. If it is the former, effective engineering approaches may be able to be taken to tune the surface tension of water so that the ice crystallization rate can be controlled.
“Our results, indeed, support the hypothesis of surface crystallization of ice in microscopic water droplets,” Dr. Li said. “Obtaining the direct evidence is our next step.”GW School of Engineering and Applied Science
Kurtis Hiatt | Newswise
Smart Data Transformation – Surfing the Big Wave
02.12.2016 | Fraunhofer-Institut für Angewandte Informationstechnik FIT
Climate change could outpace EPA Lake Champlain protections
18.11.2016 | University of Vermont
Physicists of the University of Würzburg have made an astonishing discovery in a specific type of topological insulators. The effect is due to the structure of the materials used. The researchers have now published their work in the journal Science.
Topological insulators are currently the hot topic in physics according to the newspaper Neue Zürcher Zeitung. Only a few weeks ago, their importance was...
In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.
Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
09.12.2016 | Life Sciences
09.12.2016 | Ecology, The Environment and Conservation
09.12.2016 | Health and Medicine