By Peter Weiss
It’s common knowledge that liquid water expands when it forms ice. Conversely, frozen water compacts as it melts. Now, a team of European researchers has made an ultrathin film of supercooled water that’s much denser than normal water.
The experimenters suspect that they have created the first sample of a previously hypothesized form—or phase—of water known as high-density liquid water, or HDL.
“We do not have complete proof that we’ve found this phase, but we think that it looks very promising,” says team member Simon Engemann of the Max Planck Institute for Metals Research in Stuttgart, Germany.