Lives of Spirit and Dedication

By MICHAEL D. LEMONICK.

It was in the late 1920s, only three decades after physicists had learned that atoms are built of subatomic particles, when Ernst Ruska first thought to use one such particle -- the electron -- to discern objects too small to see with conventional light microscopes. By 1931 he had built the first working electron microscope. Ruska, now retired from the Fritz Haber Institute of the Max Planck Society in West Berlin, has at long last won the Nobel Prize for his invention, which was cited by the Royal Swedish Academy of Sciences as "one of the most important of the century." Said Ruska, 79, who learned of the honor while at a health spa for treatment of rheumatism: "I am very happy indeed. I believed I was forgotten." He will receive half of the $290,000 physics award. The other half will be shared by two scientists at the IBM Zurich Research Laboratory -- Gerd Binnig, 39, a West German, and Heinrich Rohrer, 53, a Swiss -- who between 1979 and 1981 designed a new and entirely different kind of electron microscope.

Ordinary microscopes provide sharp images of most bacteria but cannot distinguish anything smaller than about eight-millionths of an inch -- the tiniest bacteria, for example -- because the wavelength of visible light, which is in the hundred-thousandth of an inch range, is too long. Ruska found that a magnetic coil could focus electrons, which have a wavelength that is roughly 100,000 times shorter. Substituting magnets for lenses and electrons for light, he built his first electron microscope. Improved versions, by providing images of viruses and even large molecules, have revolutionized such disparate fields as biology and electronics.

The scanning tunneling microscope, invented by Binnig and Rohrer, records the position of a needle that rises and dips to keep constant height while moving across the tiny irregularities on the surface of a specimen. The ups correspond to the bumps of individual atoms, and the downs to spaces between them, producing an atomic-scale contour map.

Controlling the needle's height is a minute electric current that should not flow at all, according to classical physics. Reason: there is nothing to conduct electrons, the carriers of electric current, across the insulating vacuum that separates needle from surface. But modern quantum theory says that a few electrons will jump anyway. Indeed they do, and since the number that jump depends on the size of the gap, the microscope's circuitry can continuously readjust the needle's height by monitoring the amount of current flowing between its tip and the object. The device "is completely new," said the Swedish Academy, "and we have so far only seen the beginning of its development."

With reporting by Wanda Menke-Gluckert/Bonn