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Single-atom blinking phenomenon has ORNL scientists thinking big
OAK RIDGE, Tenn.,
July 21, 2000
A whole new technology awaits exploration with the discovery of a technique for trapping single atoms, say scientists at the Department of Energy's Oak Ridge National Laboratory (ORNL).
ORNL's Mike Barnes, Thomas Thundat and Adosh Mehta have collaborated with Ramesh Bhargava of Nanocrystals Technology in Briarcliff, N.Y., to cage single europium atoms in nanocrystals not much larger than the atoms themselves. The process enables them to study the properties of a single atom at room temperature using conventional microscopy techniques. This is far more practical than methods that require cooling the atoms to cryogenic - or extremely cold - levels or trapping atoms in the gas phase using ion trap mass spectrometers.
When the atoms are trapped in a specially fabricated nanocrystal host structure, Barnes and his colleagues noticed that the europium atoms can be excited with a laser into four distinct levels of brightness. The trapping process is complex and is done by Nanocrystals Technology. Potential applications lie in computing - perhaps a four-bit optical storage system - optical sensing and display systems.
Wherever their work leads, the researchers are excited about achieving a feat that had only been achieved with single molecules rather than individual atoms.
"The problem has been that we have had to study ensembles of atoms instead of a single atom," said Bhargava, president of Nanocrystals. "Now we can look at the properties of a single atom at room temperature. It makes it much more feasible."
The blinking phenomenon occurs as the crystal structure around the trapped atom changes. A laser supplies energy for this process, which has scientists speculating about potential applications.
"We're looking perhaps at a new class of nano-scale materials with novel optical properties," said Barnes, a member of ORNL's Chemical and Analytical Sciences Division. "The challenge we face will be in controlling this process and fully understanding the mechanism."
A paper on the research was recently published in the Letters to the Editor section of the Journal of Physical Chemistry B.
Funding for the work was provided by DOE and ORNL's Laboratory Directed Research and Development program. ORNL is a DOE multiprogram research facility operated by UT-Battelle.