Water exists in two distinct liquid phases

"It is very exciting to be able to use X-rays to determine the relative positions between the molecules at different times," said researcher Fivos Perakis.
By Brooks Hays  |  June 26, 2017 at 4:18 PM
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June 26 (UPI) -- Water differs from other liquids in a variety of ways, many of which make it essential for life. New research has identified another unusual property: water exists in two distinct liquid phases.

"Water can exist as two different liquids at low temperatures where ice crystallization is slow," Anders Nilsson, a professor of physical chemistry at Stockholm University, said in a news release.

Researchers used high-powered X-rays to image water at low temperatures, revealing two distinct molecular structures. Each structure proved to represent liquid phases.

"It is very exciting to be able to use X-rays to determine the relative positions between the molecules at different times," said Fivos Perakis, a postdoctoral researcher at Stockholm University. "We have in particular been able to follow the transformation of the sample at low temperatures between the two phases and demonstrated that there is diffusion as is typical for liquids."

Most ice in the solar system doesn't exist in the solid, crystalline form found in the freezer. Most ice is amorphous and exists in two phases -- a low-density phase and high-density phase.

The latest research, published this week in the journal PNAS, suggests liquid water can exist in a pair of phases analogous to those found in ice.

"It is a dream come true to follow in such detail how a glassy state of water transforms into a viscous liquid which almost immediately transforms to a different, even more viscous, liquid of much lower density," said Katrin Amann-Winkel, a physical chemist who has been studying amorphous ice for several years.

The new findings suggest water exists at room temperature in a state of indecision or confusion, switching quickly back and forth between the two potential liquid phases.

"In a nutshell: water is not a complicated liquid, but two simple liquids with a complicated relationship," said Lars G.M. Pettersson, a professor in theoretical chemical physics.

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