Published by Communications and Public Affairs (519) 824-4120, Ext. 56982 or 53338
August 22, 2002
U of G physicists discover new form of ice
University of Guelph physicists have discovered a new form of ice that could have implications in preserving organs, embryos and other life forms.
The research by Guelph professors Bruno Tomberli, Peter Egelstaff and five other scientists appears in the Aug. 23 edition of the journal Science.
There are more than a dozen known forms of H2O, including high density and low density amorphous, or non-crystalline, ice. Previously, many scientists believed that high and low density amorphous ice came from two different states of H2O. But Tomberli, Egelstaff and the other researchers found three amorphous states of ice that exist between the high and low density forms. “The fact that we found states between the two known forms of amorphous ice suggests that there isn’t a liquid to liquid transition,” said Tomberli. “We’ve shown there isn’t a sharp boundary line between the two forms, there are intermediate states.”
Amorphous ices don’t form on Earth naturally because they only exist below —150 C, making this research of interest to astro-physicists since the ice can form in outer space. But another application for the discovery of this ice is in cryopreservation. Tissues and organs cannot be frozen in regular ice because crystals form and can damage the organisms. Because amorphous ices don’t form crystals, they could potentially be used to preserve fragile organisms. “These are non-crystalline forms of water, so by understanding them better, scientists could perhaps figure out how to not cause the water in tissues to crystallize when they’re being preserved,” said Tomberli.
The researchers came across this discovery when they were doing lengthy experiments with the high density form of amorphous ice, which is made by putting ice into a metal press and squeezing it at 13,000 times atmospheric pressure and then cooling it to —196 C using liquid nitrogen. While measuring this form of ice, they observed their sample make a transition to a form of ice that had never been recorded.
“Neuefeind [another researcher] and I were the two running the experiment and our eyebrows shot up because, before our eyes, the structure was changing from high density amorphous ice to an intermediate form,” said Egelstaff. “Our group got really excited when we realized that this was a new form of ice that we’d discovered.”
“We spent some time verifying it with different types of measurements and we were indeed able to show that this structure we had measured wasn’t some funny version of a previously existing structure, but something distinct,” Tomberli added.
The high density amorphous ice samples used in the study came from the National Research Council in Ottawa and were then shipped to the Advanced Photon Source at Argonne National Lab in Illinois where the experiments were carried out using high energy x-ray and neutron scattering.
“With x-rays what you see is a picture of the electron clouds,” said Tomberli. “The neutrons pass right through the clouds and hit the nucleus in the middle. The neutron scattering lets you see where the nuclei are. And if those two things agree with each other, which they did in our case, then you have some pretty convincing evidence that you really have seen something.”
One of the next steps could be to explore this finding more thoroughly by changing variables, such as altering the pressure and looking at the effects with chemical solutions, said Egelstaff.
The other authors of the study include Chris Tulk of Oak Ridge National Laboratory; Chris Benmore, Jacob Urquidi and Joerg Neuefeind of Argonne National Laboratory; and Dennis Klug of the National Research Council of Canada.
Contact:
Bruno Tomberli, Department of Physics
(519) 824-4120, Ext. 2718
tomberli@physics.uoguelph.ca
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