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Scientists have used high energy lasers to create a new, unique ice phase that could exist deep within Neptune and Uranus.
The structure of the water allows it to freeze in different crystalline forms (including IX ice, which does not share the same properties as Kurt Vonnegut's Ice IX). The cradle of the cat). One of the strangest forms is perhaps superionic ice, where hydrogen atoms swirl like a liquid through a solid crystal of oxygen only. Superionic ice could be important to understanding the evolution of giant ice planets. Thanks to X-rays and lasers, scientists have recently been able to produce and measure this ice in the laboratory.
The researchers first predicted the existence of superionic ice in 1988 and the first evidence of its existence in 2018. New methods now allow scientists to actually observe its structure atomic.
Scientists clamped the water molecules between a pair of diamonds and then projected the sample with six powerful laser beams into a 15 nanosecond specialized sequence using the Omega laser from the University of Rochester. This produces shock waves between the diamonds, compressing the water molecules to obtain pressures equivalent to those of the center of the Earth and a temperature corresponding to half that of the Earth's core. (One might think ice is supposed to be cold, but the material is sensitive to temperature and pressure, which means that at very high pressures, water can turn into ice at temperatures that you thought would be a liquid or a gas.) Immediately after the laser pulse, they project the sample with X-rays, which allows them to measure the structure of what they produced. The biggest challenge was to measure the sample fairly quickly after ice creation to generate an unambiguous detection signature.
"Given the extreme conditions under which this elusive state of matter is expected to be stable, compressing water at such pressures and temperatures and simultaneously taking snapshots of the atomic structure was an extremely difficult task, which required Innovative experimental concept, "author of the study, Federica Coppari said in a press release from the national laboratory Lawrence Livermore.
Image of lasers hitting a sample. Image: Millot, Coppari, Hamel, Krauss (LLNL)
And their efforts have been successful, said Coppari. There has been other evidence showing the existence of this superionic ice. But X-ray diffraction measurements are a crucial confirmation. The team proposed to name their ice cream XVIII.
"This study brings the last missing piece to the puzzle regarding the existence of superionic water ice, 30 years after the initial prediction," write the authors in the study published in Nature.
Superionic ice is more than just a curiosity. "We think this accounts for most of the mass of Uranus and Neptune," said Jonathan Fortney, director of the Other Worlds lab at the University of California at Santa Cruz, in Gizmodo. . If these planets are filled with this strange form of ice, scientists may need to rethink their models of how heat circulates in these worlds and their cooling over time.
Researchers are still hoping to take measurements at higher temperatures and pressures to completely eliminate the nature of this ice and to understand the pressures at which ice takes on this superionic form.
Our daily experiences are limited to the temperatures and pressures that are common here on Earth. It is easy to forget how many wild states of matter with strange properties can exist in other realms.
Selected Image: Millot, Coppari, Hamel, Krauss (LLNL)
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