October 12, 1999
Web posted at: 9:40 a.m. EDT (1340 GMT)

STOCKHOLM, Sweden -- Egyptian scientist Ahmed Zewail won the 1999 Nobel Prize for chemistry, the Royal Swedish Academy of Sciences said on Tuesday.

Zewail, who holds both Egyptian and U.S. citizenship and who works at the California Institute of Technology in Pasadena, was awarded the prize "for showing that it is possible with rapid laser technique to see how atoms in a molecule move during a chemical reaction," the academy said.

Hours earlier, Dutch scientists Gerardus 't Hooft and Martinus J.G. Veltman won the 1999 Nobel Prize for physics for their theoretical work on the structure and motion of subatomic particles.

The academy said Zewail's work in the late 1980s led to the birth of femtochemistry, the use of high-speed cameras to monitor chemical reactions.

"We have reached the end of the road. No chemical reactions take place faster than this," the academy said.

"We can now see the movements of individual atoms as we imagine them. They are no longer invisible," the academy said of Zewail's work.

The Dutch scientists' "work has given researchers a well-functioning theoretical machinery which can be used for, among other things, predicting the properties of new particles," the Royal Swedish Academy of Sciences said.

Their calculations were vital in calculating the mass of the top quark, which was observed for the first time in 1995 at the Fermilab in the United States.

"An important ingredient in the theory 't Hooft and Veltman have developed is an as-yet-undemonstrated particle termed the Higgs particle. In the same way as other particles have been predicted by theoretical arguments and later demonstrated experimentally, researchers are now awaiting direct observation of the Higgs particle," the academy said.

The academy planned to announce the winners of the Nobel Prize in chemistry later Tuesday.

Veltman, of Bilthoven, the Netherlands, is retired from the University of Michigan, while 't Hooft has been a professor at the University of Utrecht since 1977. Their association began in 1969 when 't Hooft studied with Veltman.

Their work has focused on the minute units making up atoms and their components.

"The two researchers are being awarded the Nobel Prize for having placed particle physics theory on a firmer mathematical foundation," the academy said in awarding the prestigious prize, worth nearly $1 million.

The Associated Press and Reuters contributed to this report.

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