Ahmed Zewail

Ahmed Hassan Zewail, was born on February 26, 1946 in Damanhour, Egypt and was raised in Alexandria. His father Hassan assembled bicycles and motorcycles and later became a government official. His parents remained married for 50 years, until Hassan died on October 22, 1992.

He received a bachelor's and an MS degree from the University of Alexandria before moving from Egypt to the United States to complete his PhD at the University of Pennsylvania with advisor Robin Hochstrasser. While at the University of Alexandria he met his wife, Mervat. She accompanied him to the University of Pennsylvania. At the university, Ahmed completed his Ph.D. and they had their first child. He completed a post-doctoral fellowship at the University of California, Berkeley with advisor Charles B. Harris.

After some post doctorate work at UC-Berkeley, he was awarded a faculty appointment at Caltech in 1976, where he has remained since, and in 1990, he was made the first Linus Pauling Chair in Chemical Physics. He became a naturalized citizen of the United States in 1982.

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.

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.