Watching the Dance of the Atoms

By Frederic Golden

Nobels for three Americans, a Japanese and a Swede

To the naked eye, inanimate objects like a block of stone or a piece of metal appear totally lifeless. But scientists see a veritable cauldron of activity in the most passive-looking object. Its atoms and molecules are in constant motion, vibrating furiously, bumping into neighbors, reeling in every direction. Though imperceptible to human senses, this chaotic ballet is critically important. Not only does it determine the very nature of observed matter (what makes a stone a stone, for example), it controls what will happen when one substance is brought together with another.

Last week the 1981 Nobel Prizes in Physics and Chemistry, worth about $182,000 each, went to five men, three Americans, a Swede and a Japanese, for helping open windows on that frenzied dance of the atoms. In their work, they used one of the more esoteric tools of 20th century science: quantum mechanics, a mathematical way of looking at the paradoxically dual nature of matter, whose smallest components sometimes behave like waves, sometimes like particles. But their results have everyday importance, for example, in the development of techniques for measuring pollution and the creation of new drugs and chemicals.

Half of the physics prize will go to Kai Siegbahn, 63, of Sweden's Uppsala University, who follows in the footsteps of his late father Karl Siegbahn, the 1924 laureate in physics.* The other half of the award will be shared equally by two Americans, Nicolaas Bloembergen, 61, a Dutch-born Harvard professor, and Arthur Schawlow, 60, of Stanford. The prize in chemistry will go to Kenichi Fukui, 63, of Japan's Kyoto University, and Roald Hoffmann, 44, of Cornell University.

Once again the U.S. did well in the Nobel rivalry. Including the previously announced prize in medicine, in which two of the three winners were American (Caltech's Roger Sperry and Harvard's David Hubel), the U.S. this year can claim five of the eight science laureates, as well as the economics prize.

All three 1981 physics winners were cited for contributions to spectroscopy, a basic tool for studying atoms and molecules that dates back to the moment when Sir Isaac Newton passed a beam of sunlight through a prism and found that it was split into a rainbow of colors, a spectrum. Newton's successors discovered that any material heated to incandescence not only produces a spectrum but one so distinctive that it could be used like a fingerprint for identifying the substance. Astronomers soon found that the spectra of distant stars yielded all manner of information, including the star's composition, age, temperature, motion, magnetic field, even whether it was a single or double star.

Yet spectra can also be created by directing a light beam or, say, X or gamma rays at an object. As the radiant energy strikes the atoms, their electrons hop from one orbit (or, in the language of quantum mechanics, one energy level) to another, absorbing or emitting light at specific frequencies. Such spectra yielded invaluable data about atomic and molecular structure.

By the late 1930s, however, conventional spectroscopy had run into difficulties.

Ordinary light was not a powerful or precise enough probe to penetrate the atom's inner secrets. In 1958, while he was still a researcher at Bell Labs, Schawlow helped overcome that obstacle. With his brother-in-law Charles Townes, he devised a way to build a practical laser, a device for creating narrow, intense, single-frequency beams of so-called coherent light. Like soldiers in a line of march, each successive light wave was exactly in step with the next. In 1964, Townes and two Soviet researchers won a Nobel for spelling out the underlying theory of lasers and their microwave antecedent, masers. But it was Schawlow and Bloembergen who led the way in applying the powerful new light to spectroscopy. One of Schawlow's notable feats: studying the simplest of all elements, hydrogen, with hitherto unattainable precision. Bloembergen extended the exploratory range of lasers far beyond the realm of visible light by mixing three beams to produce a fourth one of exceptionally long or short wave length.

Starting in the 1950s, Siegbahn developed a related analytic technique called electron spectroscopy. Scientists had long known that when ultraviolet light or X rays strike atoms, they dislodge electrons.

But as the electrons break away from their accustomed orbits, they collide with other electrons, creating spectra that are hopelessly blurred. Siegbahn overcame these difficulties by devising an ingenious new focusing device. For the first time, it was possible to observe the faint tracks left by electrons that had managed to escape unscathed. Among many applications: the ability to measure infinitesimally small signs of surface corrosion on metals.

The two chemistry winners, Fukui and Hoffmann, worked toward the same goal but half a world apart. Their aim: to determine exactly why certain chemical reactions between atoms and molecules can occur and others cannot. More than 25 years ago, Fukui developed a theory of "frontier orbitals," showing that the orbits of the most loosely bound, or outermost, electrons play an unexpectedly large role in the reactivity of molecules. Fukui's ideas were at first brushed off by his Japanese colleagues, in part, he suspects, because they had not originated in the U.S. or Europe. But by the mid-1960s, Hoffmann, who had come to the U.S. at eleven after a harrowing childhood in Nazi-occupied Poland, independently reached the conclusion, similar to Fukui's, that a reaction is more likely to occur if the molecules or atoms are likely to have the same orbital properties after they join as they had before. In other words, nature wants to conserve what scientists call orbital symmetry. The theoretical rules that resulted from the work of the two researchers helped chemists predict whole classes of previously inexplicable reactions in the lab. Hoffmann, however, never works in the chem lab himself, and Fukui does so rarely. Explains Hoffmann: "We use mathematics, physics, computers and a great deal of thinking." A noble understatement.

--By Frederic Golden.

Reported by Mary Johnson/ Stockholm and S. Chang/Tokyo

* The Siegbahns are the sixth family in which parent and child have been Nobel laureates. The most prominent are the Curies. In 1903 Marie and Pierre Curie shared the physics prize; 32 years later, Daughter Irene and Son-in-Law Frederic Joliot-Curie won in chemistry.

With reporting by Mary Johnson, S. Chang

This file is automatically generated by a robot program, so viewer discretion is required.