By transferring a single electron to a gold atom, scientists have converted a neutral atom into a negatively charged ion. The switching of the electronic state of an individual atom is not only a demonstration of the exquisite control over matter that scientists now wield but could also lead to new ways of encoding data for making ultrahigh-density memory chips.
Jascha Repp of the IBM Zurich Research Laboratory in Switzerland and his colleagues allowed gold atoms to adsorb onto a thin film of sodium chloride atop a copper base. Then, they finessed the styluslike tip of a scanning tunneling microscope to a position directly over one gold atom and applied a positive-voltage pulse. This pulse delivered an electron to the atom, tagging the gold atom with a negative charge. Applying a negative voltage to the tip yanked the electron back, returning the gold atom to its neutral state.
Reporting in the July 23 Science, the researchers suggest that such an atomic-switching mechanism could be used to store bits of data—neutral atoms might encode the 1s of digital data, for instance, while charged atoms would encode the 0s.
Zurich Research Laboratory
Horn, K. 2004. Charging atoms, one by one. Science 305(July 23):483-484. Summary available at [Go to].