Researchers were able to use a laser to refrigerate water, as well as other liquids, under real-world conditions for the first time since laser was invented in 1960. Lasers have been used more as a heating tool in the past.
The study, published in the Journal Proceedings of the National Academy of Sciences, shows how the team used an infrared laser to cool water down to 36 degrees Fahrenheit, considered a major breakthrough in the field that solves a decades-old puzzle. This refrigeration process was first demonstrated in vacuum conditions back in 1995, although it took 20 years to be demonstrated in liquids.
“Typically, when you go to the movies and see Star Wars laser blasters, they heat things up. This is the first example of a laser beam that will refrigerate liquids like water under everyday conditions,” said lead author Peter Pauzauskie. He added that it wasn’t clear if such enterprise could be done, because usually water gets warmer when it illuminated.
How it works
The team used infrared light for the cooling laser, keeping in mind possible biological applications because visible light could damage the cells. By using the laser, they were able to refrigerate saline solution and other components used in genetic and molecular research.
In order to conduct the study, the research team used a material found in commercial lasers, but they reversed the laser phenomenon. By illuminating a single tiny crystal suspended in water with infrared light, it produced a “unique kind of glow” that has slightly more energy than the energy it absorbs. This energy glow drives heat away from both the crystal, and the water surrounding it.
A large possible application field
The recent discovery could make industrial users cool certain areas by using a focused point of light, a major help in, for example, the building of microprocessors. A laser beam could be implemented to cool specific components in computer chips, preventing dangerous cases of overheating, keeping the information safe.
Also, it could be used to accurately cool a portion of a cell, as it divides or repairs itself, slowing down the process and allowing scientists to study how it works. Another possible utility could be the cooling of a single neuron in a network, silencing it without producing any harm, to observe how its fellow-neurones bypass is and reunite themselves.
Pauzauskie explained that scientists have a great interest in how cells divide themselves, and how molecules and enzymes work, stating that using laser cooling will provide them with the opportunity to study its behavior without producing any harm to these structures.
What comes after?
Although growing laser crystal is quite expensive, researchers demonstrated that a low-cost hydrothermal process can be used to build laser crystal for the refrigeration process in a faster and cheaper way. Also, they designed an instrument that holds the nanocrystal surrounded by water in order to be illuminated, and they added a thermometer, that uses color, allowing scientists to follow the process in real time.
“Few people have thought about how they could use this technology to solve problems because using lasers to refrigerate liquids hasn’t been possible before. We are interested in the ideas other scientists or businesses might have for how this might impact their basic research or bottom line,” Pauzauskie concluded.
Source: University of Washington Today