The Infinitesimal Gets Smaller; July 1997; Scientific American Magazine; by Gibbs; 1 Page(s)

Not so long ago, atoms seemed infinitesimal; even the most powerful microscopes could not quite make them out. Then physicists discovered that by dragging a supersharp needle across a surface, they could sketch atomic outlines for all to see. The boundary of the infinitesimal receded to subatomic particles, in particular the electron, which is to an atom what a sperm cell is to a basketball.

In April, physicists at Lucent Technologies¿s Bell Laboratories announced that they had briefly crossed that tiny frontier by running wires down either side of the sharpened glass needle on their scanning probe microscope. The wires connect at a flat tip just 500 atoms wide, forming a single electron transistor so sensitive that it can detect one hundredth of an electron charge. Moving the instrument across a surface doped with silicon ions (similar to a microchip), the researchers produced this image of the atoms¿ electrical fields, which consist of clumps of electrons (see http://www.lucent.com/press/0497/970425.bla.html). By shooting light at the atoms and then comparing how the images change, the group claims to have seen individual electrons moving about. The investigators expect to be able to boost the power of the device by a factor of 100 and thereby image single electrons more directly--a view that could reveal the secrets of exactly how charges move in semiconductors. Now if only we knew what quarks look like. . ..