The concept of laser cooling is three decades old, but German researchers have finally leaped beyond previous failures to show that bombarding high-pressure gas with a laser can produce dramatic cooling.
Reporting their findings last week in Nature, the researchers were able to drop the temperature as much as 66 degrees Celsius — or about 119 degrees Fahrenheit — in mere seconds.
The ability to cooling dense gases with lasers may offer a new kind of refrigeration — possibly one that can achieve temperatures close to absolute zero.
So how does laser cooling work? Using the right kind of laser on gas molecules excites their electrons into higher-than-normal orbits.
“In this process the electron orbits of the particles ‘bend,’ ” said University of Bonn physicist Martin Weitz in a statement. “At the time of the collision, you therefore need less energy than normal in order to vault the electron into a high orbit.”
Once the collision occurs, the orbits return to their normal shape. In turn, electrons have to absorb energy to stay in the new higher orbit — and as they absorb extra energy, the gas particles slow down, dropping the temperature.
The benefit to them? The ability to play with gases in “new, previously unexplored states of matter.”