First Picture of an Atom's Shadow—Smallest Ever Photographed
Technique might help turn atoms into vehicles for secret messages.
(Extreme Scientific Imaging: Best of 2011 Named.)
The pioneering shutterbugs used an electrical field to suspend a charged atom, or ion, of the element ytterbium in a vacuum chamber. They then shot a laser beam—about a thousand times wider than the atom—at the ytterbium.
The ytterbium atom absorbed a tiny portion of the light, and the resulting shadow was magnified by a lens attached to a microscope, then recorded via a digital camera sensor.
The team used ytterbium because they knew they could create lasers of the right color to be strongly absorbed by the element.
"Each element responds to different specific wavelengths ... so we would need different laser systems to use this technique on a different atom," said study leader
