Muslim Scientist Ahmed Hassan Zewail

Ahmed Hassan Zewail

Ahmed Hassan Zewail is an Egyptian scientist, known as the "father of femtochemistry", he won the 1999 Nobel Prize in Chemistry for his work on femtochemistry and became the first Arab scientist to win a Nobel Prize in a scientific field.

He is the Linus Pauling Chair Professor of Chemistry, Professor of Physics, and the director of the Physical Biology Center for Ultrafast Science and Technology at the California Institute of Technology. The breakthrough created a new field of physical chemistry known as femtochemistry.

Chemist Ahmed H. Zewail was born February 26, 1946, Damanhur, Egypt and was raised in Desouk. His father Hassan assembled bicycles and motorcycles and later became a government official. His parents stayed married for 50 years, till the death of his father in October 22, 1992.

He received a Bachelor of Science and Master of Science degrees in Chemistry from the Alexandria University before moving to the United States to complete his PhD at the University of Pennsylvania supervised by Robin M. Hochstrasser.

After completing his PhD, Zewail did postdoctoral research at the University of California, Berkeley supervised by Charles Bonner Harris. Following this, he was awarded a faculty appointment at the California Institute of Technology in 1976, where he has remained since 1990, he was made the first Linus Pauling Chair in Chemical Physics. He became a naturalized citizen of the United States in 1982.

Zewail has been nominated and will participate in President Barack Obama's Presidential Council of Advisors on Science and Technology (PCAST), an advisory group of the Nation's leading Scientists and Engineers to advise the President and Vice President and formulate policy in the areas of science, technology, and innovation.

Zewail's key work has been as a pioneer of femtochemistry i.e. the study of chemical reactions across femtoseconds. Using a rapid ultrafast laser technique (consisting of ultrashort laser flashes), the technique allows the description of reactions on very short time scales - short enough to analyse transition states in selected chemical reactions.

His work started with the question, how fast did the energy within an isolated large molecule like naphthalene redistribute among all the atomic motions? They had to build an apparatus with a vacuum chamber for molecules coming out of the source as a collimated beam at supersonic speed.

The challenge was to build an ultrafast laser to be used with the molecular beam. The beam and the picosecond laser system were interfaced. The goal of the project began as wanting to directly measure the rate of vibrational-energy redistribution for an isolated molecule using the picosecond laser.

They wanted to see the process from birth to death of a molecule. In this experiment the isolated anthracene molecule was unexpected and contrary to popular wisdom. During redistribution the population was oscillating coherently back and forth. There was no decay, but there was rebirth and all molecules moved coherently in a phase. In a large molecule, each vibrational motion is like a pendulum, but there are many motions because a molecules has many atoms. If the motions were not coherent, the observation would have been much different.

The results of this experiment revealed the significance of coherence and its existence in complex molecular systems. The finding of coherence were significant because it showed that through the expected chaotic motions in molecules, ordered motion can be found, despite the presence of a "heat sink", which can destroy coherence and drain energy. Coherence in molecules had not been observed before not because of a lack of coherence, but because of a lack of proper probes. In the anthracene experiments, time and energy resolutions were introduced and correlated.

Though Zewail continued studies on vibrational-energy redistributions, he started new studies on shorter time resolutions for molecules showing different chemical processes and rotational motions.