ROBERT SIEGEL, HOST:
We're going to chill out now with some ice research. All the ice you know and love from the ice cubes in a drink to the polar ice caps - all of it has the same basic internal structure. But as NPR's Nell Greenfieldboyce reports, scientists have just observed a kind of ice that is unlike anything seen before.
NELL GREENFIELDBOYCE, BYLINE: Pretty much all the ice on earth is what's known as hexagonal ice. Its water molecules are arranged in a hexagonal pattern. This sixfold symmetry is why snowflakes have six arms. But it is possible to take water and create other forms of ice. Andre Geim is a physicist at the University of Manchester in England. And when he was recently looking around for a new project, he decided to try to make a weird, new form of ice at room temperature.
ANDRE GEIM: So we are looking what to do next, and two-dimensional ice, two-dimensional water was an obvious direction.
GREENFIELDBOYCE: Two-dimensional ice seemed obvious to him because he did groundbreaking research on another two-dimensional material called graphene. Graphene is a single layer of carbon atoms. Its structure looks like chicken wire. Geim and a colleague first isolated it by peeling it off ordinary graphite using Scotch Tape. That won them a Nobel Prize, even though Geim is probably more famous for once using a magnetic field to levitate a frog. Geim says making two-dimensional ice turns out to be easy. They took a sheet of graphene, which has unusual properties...
GEIM: ...Put a tiny, tiny droplet of water on top...
GREENFIELDBOYCE: ...Then laid another sheet of graphene on top of that like a sandwich. And then they examined the water that was trapped inside.
GEIM: And to our own surprise, we found exactly what theory predicted - an ice which is only one atom thick.
GREENFIELDBOYCE: Not only that, the water molecules were arranged in a lattice of squares.
GEIM: And that is the thing that's quite surprising because I don't think it's been observed before.
GREENFIELDBOYCE: Alan Soper is a physicist at the Rutherford Appleton Laboratory also in the U.K. He says almost all known forms of ice including our everyday hexagonal ice have an underlying structural motif of water molecules that are arranged in little triangular pyramids. This square ice doesn't have that.
GEIM: It's quite interesting that even today we are able to come up with new scenarios for water that we haven't previously thought of.
GREENFIELDBOYCE: Although, he says, it's not yet clear if there's any practical applications for this one. A report of the ice appears in the journal "Nature." Nell Greenfieldboyce, NPR News.
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