Boundary structure between Ih- and Ic-stacking domains on the (0001) surface of hexagonal ice. Credit: Nature (2024). DOI: 10.1038/s41586-024-07427-8
A team of physicists associated with several institutions in China has discovered the reason for the ice slide. In their study, published in the journal Naturethe group used atomic force microscopy to take a closer look at the surface of the ice at different temperatures.
Previous research and much anecdotal evidence have shown that ice is slippery, even when temperatures are well below freezing. Research has suggested that this is due to a pre-melted layer developing on the surface, which serves as a lubricant.
In this new study, the research team used an atomic force microscope equipped with a carbon monoxide atom at its tip to get a better look at the structure of normal ice and its coating before melting.
The researchers started by cooling the ice inside the microscope chamber to -150C and then using the microscope to see its atomic structure. They could see that the interior ice (known as Ih ice) and the ice on the surface were different.
Ice Ih was, as expected, arranged in stacked hexagons. In contrast, the ice on the surface was only partially hexagonal. The researchers also found faults in the ice at the boundary between the two types of ice that occurred when the different forms of ice met each other.
The researchers then slightly raised the temperature in the room, which resulted in more disorder as the changes in shape became more pronounced. The team then created a simulation showing how such a disturbance would affect the surface as a whole. It showed that the disturbance extended across the surface, giving the ice a liquid appearance that would be slippery if stepped on.
The research team explains that the reason their experiments were done at such low temperatures was that the microscope had to be operated in a vacuum; warmer temperatures would have led to sublimation, making it difficult to study ice at the atomic level.
They also note that they plan to continue their study by using short laser bursts to heat the ice for a very short time, allowing them to see what happens under warmer conditions.
More information:
Jiani Hong et al, Atomic resolution imaging of surface structure and premelt of ice Ih, Nature (2024). DOI: 10.1038/s41586-024-07427-8
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citation: Atomic resolution imaging shows why ice is so slippery (2024, May 23) Retrieved May 24, 2024 from https://phys.org/news/2024-05-atomic-resolution-imaging-ice-slippery.html
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