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17 April 2014 12:48 pm ,
Vol. 344 ,
Using the two high-quality genomes that exist for Neandertals and Denisovans, researchers find clues to gene activity...
A new report from the Intergovernmental Panel on Climate Change (IPCC) concludes that humanity has done little to slow...
Astronomers have discovered an Earth-sized planet in the habitable zone of a red dwarf—a star cooler than the sun—500...
Three years ago, Jennifer Francis of Rutgers University proposed that a warming Arctic was altering the behavior of the...
Officials last week revealed that the U.S. contribution to ITER could cost $3.9 billion by 2034—roughly four times the...
An experimental hepatitis B drug that looked safe in animal trials tragically killed five of 15 patients in 1993. Now,...
- 17 April 2014 12:48 pm , Vol. 344 , #6181
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Trapped by Lasers
6 January 2000 7:00 pm
The first scientist to use lasers to trap tiny spheres published his groundbreaking study 29 years ago this month. His research led to the development of "optical tweezers," laser-based devices that can manipulate small particles and detect the forces of single molecules, and to Nobel Prize-winning work on using lasers to trap atoms.
Physicist Arthur Ashkin of the Bell Telephone Laboratories in Holmdel, New Jersey, shot a laser beam through a container of water filled with microscopic latex spheres. He found that the spheres were drawn from the edge of the beam toward its center, then were pushed in the direction of the beam's moving photons by so-called radiation pressure. Pointing two laser beams at each other created a stable trap for the spheres, he reported in the 26 January 1970 issue of Physical Review Letters.
"Art had a huge influence on both the field of optical tweezers and atom trapping," says William Phillips, a physicist at the National Institute of Standards and Technology in Gaithersburg, Maryland. Optical tweezers use a tightly focused laser to manipulate microscopic particles. They can gauge the delicate forces of single molecules on a particle based on its slight displacement from the laser's focus. For example, in the past decade researchers used optical tweezers to measure the push and pull between two molecules involved in muscle contraction: myosin and actin. As for atom trapping and cooling, says Phillips, who won a share of the Nobel Prize in physics last year for this kind of work, Ashkin had "a lot of the key ideas."