Super-Fast Laser Reveals Super-cooled Water's Secrets
Scientists are now using an ultrafast laser to tease out for the first time the details of water’s bizarre super-cooled behavior and structure.
Water is wonderful and weird. It’s more dense than ice, it holds tremendous heat, and its surface tension is so strong it’s like a force field…sort of.
It also can stay liquid at temperatures welllll below freezing (-51F) if it’s pure enough so no seed-like nucleation sites exist for crystal formation. The already bizarre properties of water are amped-up even more in this super-cooled state but it’s been fiendishly difficult to get there and take a close look because pesky ice starts forming.
This super-cooled no-mans-land has now opened its gates to us thanks to a scientific double-tap. First a vacuum super-cools water droplets, then a femto-second laser (quadrillionths of a second) explodes a droplet but not before creating a diffraction pattern that reveals the never-before-seen molecular structure of liquid water right before it freezes.
There’s much to learn but so far they’ve discovered that as water becomes super-cooled, it molecular arrangement changes. The colder it gets the more this change accelerates. It also actually creates two different types of liquid water, one denser than the other.
Further exploration could reveal why water is so weird at all temperatures, not just super-cooled ones. We could even further elucidate its tremendous impact not only on biology but climate change as well.
All I know is that I’m gonna look long and hard at my next glass of water.
Image Credit: Greg Stewart / SLAC