Tuesday, October 12, 1999 Published at 14:44 GMT 15:44 UK
'Slow motion' chemist grabs Nobel
Egyptian-born scientist Ahmed Zewail has been awarded the 1999 Nobel Prize for Chemistry for developing what amounts to a highly sophisticated form of flash photography.
The California Institute of Technology researcher pioneered a laser technique that allows scientists to see, in "slow motion", how atoms and molecules behave in chemical reactions.
In a series of ground-breaking experiments in the 1980s, he developed what many have described as the world's fastest camera - a device that provides a laser flash measured in femtoseconds.
This is a unit of measurement equal to 0.000000000000001 seconds, which is to a second what a second is to 32 million years. But this is the sort of speed required if chemists want to "freeze" the moment when atoms and molecules come together to form new compounds.
One of the first major discoveries to come from it was the realisation that as chemical reactions proceed intermediate products are formed that are quite distinct from the reactants and final products.
Announcing the Nobel Prize, the Royal Swedish Academy of Sciences said Ahmed Zewail was being honoured for creating a "revolution" in chemistry.
"Scientists the world over are studying processes with femtosecond spectroscopy in gases and in solids, on surfaces and in polymers," it said.
The award, which has been predicted for several years, will be welcomed across the sciences.
"It's really exciting," said Professor David Clary, from University College London, UK, who has worked on the theory behind Professor Zewail's experiments.
"He was the first person to find out how long it takes for bonds to break in molecules and for bonds to form. He quantified it. And he's applied this knowledge to a whole range of interesting problems all the way from chemical reactions important in the atmosphere, going up to reactions involving DNA bases and haemoglobin."
Ahmed Zewail was born in 1946 in Egypt where he grew up and studied at the University of Alexandria. He got his PhD in 1974 at the University of Pennsylvania. Since 1990, he has been employed at Caltech, where he has the Linus Pauling Chair of Chemical Physics.
Although much of his research career has been spent in the US, he is well known in Egypt, where his face has appeared on postage stamps.
The prize is worth around £600,000 and will be given to Ahmed Zewail in Stockholm on 10 December by King Carl XVI Gustaf of Sweden.