Yuan Tseh Lee

Yuan Tseh Lee, born in 1936, Taiwanese-American chemist and Nobel Prize winner. Lee revolutionized chemical research with a molecular-beam (narrow stream of molecules in a vacuum) apparatus that could detect any molecule. This device made it possible to detail the precise motion of atoms during chemical reactions. Lee was awarded the 1986 Nobel Prize in chemistry for his important contributions to molecular-beam technology. The award was shared with American chemist Dudley Robert Herschbach and German-born Canadian chemist John Charles Polanyi.

Born in Hsinchu, Taiwan, Lee proved to be such an excellent student that he was admitted to the National Taiwan University without an entrance examination. He came to the United States in 1962, and in 1965 received his Ph.D. degree from the University of California at Berkeley. Lee moved to the University of Chicago in 1968 and became a full professor in 1973. He continued to use crossed molecular beams to study more-complex reactions, including the collisions between rare gas atoms. In 1974, the year he became an American citizen, he was made professor of chemistry at the University of California’s Lawrence Berkeley National Laboratory. His work at Berkeley included the application of photon beams in chemical reactions.

In 1966 Lee designed and built an apparatus that measured the product of reactions (the molecules scattered by collision). The following year, he joined the Harvard University research team headed by Herschbach, who had developed a molecular-beam apparatus. Two beams, each containing a different molecule, were directed through a vacuum chamber at the same speed and angle to create a reaction. A filament detected the scattered postreaction product. Using this device, it was possible to measure the angle at which a molecule leaves a collision. However, the apparatus was limited because its detector picked up only alkali molecules. Aided by Herschbach, Lee devised a molecular-beam instrument with a universal detector that separated the paths of individual atoms so that they could be identified easily. This made possible the study of any chemical reaction, even between large molecules, and enabled scientists to control reaction conditions exactly. At about the same time that Lee made his discoveries, Canadian chemist John C. Polanyi developed a complementary method that measured the transitional energy states of the reaction product.