Laser Beams Refrigerate Water in University of Washington Study

Summary: Infrared laser beams refrigerate water, according to a University of Washington study in Proceedings of the National Academy of Sciences Nov. 20, 2015.

During cooling by the laser, nanocrystals developed by the University of Washington team emit a reddish-green "glow" that is visible to the naked eye: Dennis Wise/University of Washington, usage restrictions: with credit, via EurekAlert!

Laser beams are able not only to heat things up but also to cool them down, according to a study published Nov. 20, 2015, by the Proceedings of the National Academy of Sciences for the multidisciplinary journal’s preprinted edition.

The study’s five co-authors base their findings upon their experiments with infrared laser beams cooling water by about 2.2 degrees Celsius (36 degrees Fahrenheit). The results of the experiments confirm and contradict previous research. They describe the refrigeration of water under everyday conditions and parallel earlier research regarding the laser refrigeration of bulk crystals in vacuums to temperatures around 90 degrees Kelvin (minus 183.15 degrees Celsius, minus 297.67 degrees Fahrenheit).

And yet lasers since the earliest experiments always emit heat.

Co-author Peter J. Pauzauske, assistant professor of materials science and engineering in Seattle at the University of Washington and scientist at the U.S. Department of Energy’s Pacific Northwest National Laboratory in Richland, finds: “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. It was really an open question as to whether this could be done because normally water warms when illuminated.”

Experiments with lasers heating things up go back to 1960 whereas those with beams cooling things down go back to demonstrations of 1995 at New Mexico’s Los Alamos National Laboratory.

The experiments in University of Washington laboratories have practical applications and theoretical implications even though cooling lasers may be available far later, not imminently early, in the 21st century. Immediate commercialization of the development, which runs “the laser phenomenon in reverse,” is postponed by the high costs, high power and intensive energy implicit in cooling laser beams with multiple crystals. Co-researchers Matthew J. Crane of the department of chemical engineering, Peter J. Pauzauskie, Paden B. Roder of the department of materials science and engineering, Bennett E. Smith of the department of chemistry and Xuezhe Zhou of the department of materials science and engineering judge designing the proper instrumentation and devising the proper method major hurdles already overcome.

Microscopic tractor beam-like laser traps keep one nanocrystal in place in a liquid-filled chamber for illuminating and interpreting its shadow as the liquid cools and the crystal changes from warmer blue-green to cooler red-green. The instrumentation and the method let the co-researchers refrigerate cell culture media and saline solutions featured in genetic and molecular research. The low-cost hydrothermal process may halt biological, defensive and telecommunications-lasered application meltdown.

Dr. Pauzauskie notes: “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.”

University of Washington engineers -- (from left) Peter Pauzauskie, Xuezhe Zhou, Bennett Smith, Matthew Crane and Paden Roder (unpictured) with their invention, an instrument that uses infrared laser light, for the first time, to refrigerate liquids: Dennis Wise/University of Washington, usage restrictions: with credit, via EurekAlert!

Acknowledgment

My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet.

Image credits:

nanocrystals' reddish green glow: Dennis Wise/University of Washington, usage restrictions: with credit, via EurekAlert! @ http://www.eurekalert.org/multimedia/pub/103463.php?from=311951

University of Washington engineers -- (from left) Peter Pauzauskie, Xuezhe Zhou, Bennett Smith, Matthew Crane and Paden Roder (unpictured) with their invention, an instrument that uses infrared laser light, for the first time, to refrigerate liquids: Dennis Wise/University of Washington, usage restrictions: with credit, via EurekAlert! @ https://www.eurekalert.org/multimedia/pub/103462.php?from=311951

For further information:

Langston, Jennifer. 16 November 2015. "UW team refrigerates liquids with a laser for the first time." UW Today.
Available @ http://www.washington.edu/news/2015/11/16/uw-team-refrigerates-liquids-with-a-laser-for-the-first-time/

NewsBeat Social. 23 November 2015. "Scientists Create Real-Life Freeze Ray." YouTube.
Available @ http://www.youtube.com/watch?v=vXVgtJFrtlo

Roder, Paden B. "Laser refrigeration of hydrothermal nanocrystals in physiological media." Proceedings of the National Academy of Sciences of the United States of America, vol. 112, no. 49 (Dec. 8, 2015):15024-15029. DOI: 10.1073/pnas.1510418112
Available @ http://www.pnas.org/content/112/49/15024.abstract

VOA News.23 November 2015. "Defying Logic, Lasers Used to Refrigerate Water." Voice of America > Science & Technology.
Available @ http://www.voanews.com/content/mht-lasers-used-to-refrigerate-water/3070351.html