Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

The smallest piece of ice reveals its true nature

22.06.2007
Collaborative research between scientists in the UK and Germany (published in this week’s Nature Materials) has led to a breakthrough in the understanding of the formation of ice. Dr Angelos Michaelides of the London Centre for Nanotechnology (formerly of the Fritz-Haber Institut der Max-Planck Gesellschaft in Berlin) and Professor Karina Morgenstern of the Leibniz University Hannover have combined experimental observations with theoretical modelling to reveal with unprecedented resolution the structures of the smallest pieces of ice that form on hydrophobic metal surfaces.

The results provide information about the process of ice nucleation at a molecular level and take science a significant step closer to understanding the mysterious process through which ice forms around microscopic dust particles in the upper atmosphere. Because this is the basis of cloud formation, knowing how different particles promote ice formation is crucial for climate change models.

The authors began by cooling down a metallic surface to 5 degrees above absolute zero (around –268 Celsius) at which temperature it was possible to “trap” and obtain images of the smallest possible pieces (hexamers) of ice using a scanning tunnelling microscope (STM). The hexamer – the simplest and most basic “snow flake” – is composed of just six water molecules. Other ice nanoclusters containing seven, eight and nine molecules were also imaged.

On the difficulties of imaging these ice clusters, Prof Morgenstern said: “Scientists have long struggled to resolve single water molecules within ice clusters, because they are so vulnerable to damage induced by electrons – the very thing that creates the image. The high resolution could only be achieved by reducing the current to the smallest value technically possible.”

As well as performing experiments, the team used highly-accurate (‘first principles’) theoretical models to analyse how such a structure could form. Here the theory provided some surprising insights. In ice, water molecules usually bond to each other with equal strength but with the ice nanoclusters the team identified a pattern of alternating shorter and longer bonds between the water molecules. This pattern provided new information about the ability of water molecules to share their hydrogen bonds, revealing a hitherto unknown competition between the ability of water molecules to bind to a metal surface and simultaneously accept hydrogen bonds.

Dr Michaelides said, “We are all familiar with the freezing of water. It features prominently in our daily lives, from fridge freezers to winter snow. Despite all this, the question of how individual water molecules come together and give birth to ice crystals remains mysterious. Our research provides an insight into the most important and ubiquitous type of ice nucleation event, namely heterogeneous nucleation. State-of-the-art experimental and theoretical techniques allowed us to “watch” and accurately model what happens at very low temperatures.”

The research makes it possible to explain the ways in which water structures form on different substrates, such as transition metals and salt surfaces. It may also provide a new way of thinking about the structure of ice clusters that form on solid surfaces in general, opening the door for applications in a variety of fields as diverse as astronomy, electrochemistry, and energy research. It also takes us a step closer to understanding how water interacts with different aerosols and dust particles in the atmosphere, processes which drive cloud formation and have a large impact on the planet’s climate.

David Weston | alfa
Further information:
http://www.ucl.ac.uk

More articles from Physics and Astronomy:

nachricht A better way to weigh millions of solitary stars
15.12.2017 | Vanderbilt University

nachricht A chip for environmental and health monitoring
15.12.2017 | Friedrich-Alexander-Universität Erlangen-Nürnberg

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: First-of-its-kind chemical oscillator offers new level of molecular control

DNA molecules that follow specific instructions could offer more precise molecular control of synthetic chemical systems, a discovery that opens the door for engineers to create molecular machines with new and complex behaviors.

Researchers have created chemical amplifiers and a chemical oscillator using a systematic method that has the potential to embed sophisticated circuit...

Im Focus: Long-lived storage of a photonic qubit for worldwide teleportation

MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.

Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...

Im Focus: Electromagnetic water cloak eliminates drag and wake

Detailed calculations show water cloaks are feasible with today's technology

Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...

Im Focus: Scientists channel graphene to understand filtration and ion transport into cells

Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.

To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...

Im Focus: Towards data storage at the single molecule level

The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.

Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

AKL’18: The opportunities and challenges of digitalization in the laser industry

07.12.2017 | Event News

 
Latest News

Engineers program tiny robots to move, think like insects

15.12.2017 | Power and Electrical Engineering

One in 5 materials chemistry papers may be wrong, study suggests

15.12.2017 | Materials Sciences

New antbird species discovered in Peru by LSU ornithologists

15.12.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>