Single gold atoms altered

Scientists from IBM's Zürich Research Laboratory and Chalmers University of Technology in Sweden have found a way to alter a single atom.

The researchers used a low-temperature scanning tunneling microscope and a voltage pulse to place an electron on an individual gold atom, then remove the electron. Regular atoms are neutral, while ions -- atoms with more or fewer electrons -- carry a charge.

The gold atom, positioned on an ultrathin film of sodium chloride, remained stable during the operation, despite the change in charge. The gold atom was kept stable by small changes in the positions of nearby atoms in the film.

Ions have different chemical and physical properties than corresponding neutral atoms. Being able to switch an individual atom to an ion and back promises a new way to control attributes like chemical reactivity, optical properties, and magnetic properties, according to the researchers.

This control could eventually lead to devices that work at the atomic scale, like a nonvolatile memory cell that stores information in a single atom. Practical atomic-scale memory would increase the amount of data that can be stored in a given area by 10,000 times, according to the researchers.

Charged atoms can be used to influence nearby molecules as well, according to the researchers.

The work appeared in the July 23, 2004 issue of Science.