Optical "centrifuge" gives particles a whirl

17 Jun 2002

For the past 25 years, physicists wanting to pick up and hold particles as small as a single molecule have used very precise laser beams in setups known as "optical tweezers." Now two teams of researchers, in the United Kingdom and in Australia, have found that by using specially sculpted laser beams they can do more than just hold a molecule: They can make it spin, speed up and slow down its spinning, and even bring it to a stop and spin it the other way. The researchers say the technique may one day be useful in nanotechnology and, because it requires less power than conventional optical tweezers, can be used to manipulate living biological tissue without killing it. The results are reported in the recent issue of Science