Ahmed Hassan Zewail (1946–2016) Nobel-Winning Inventor of Femtochemistry and Statesman

COMMENT OBITUARY Ahmed Hassan Zewail (1946–2016) Nobel-winning inventor of femtochemistry and statesman.

hat the first science Nobel the view that science transcends prizewinner from the political borders. One early inci- Arabic-speaking world, dent illustrates this. In January TAhmed Hassan Zewail, pioneer 1983, he organized the Inter- of ultrafast chemistry, was also national Conference on Photo a diplomat is apparent in his chemistry and Photobiology at unique list of distinctions. Few his alma mater in Alexandria. scientists can have been gar- He was clearly a rising star, but the landed by foundations in both work that would lead to the Nobel Israel and Saudi Arabia, served had barely started. The confer- in the Pontifical Academy of ence was a major milestone in Sciences — and had their face his career, attracting a stunning on several postage stamps while collection of distinguished inter- living. He died on 2 August 2016, national scientists, with an obvious aged 70. subtext of bootstrapping progress The eldest child of a middle- for Egyptian science in general. class family, Zewail was born on Given the tumultuous politics 26 February 1946. He grew up of the region then, as now, it was in Desouk, Egypt, a small town no surprise that as soon as Israeli

CALTECH 80 kilometres from Alexandria. scientists arrived, most of the After a state-school education, Arab representatives were ordered he took undergraduate and masters degrees that the dominant force was intramolecular by their governments to leave. Zewail surely in chemistry at the University of Alexan- relaxation, and that this was largely would have expected this and could have dria. He then decided to further his studies incoherent. taken the easy way out — asking his Israeli in the United States, despite a fairly weak Zewail’s work shattered this picture. friends (who were numerous) to stay away. command of English (a fact which shocks Through elegant experiments, his group Instead he publicly denounced at the con- those of us who knew this eloquent speaker unravelled reaction dynamics, clarified ference the destructive acts of the same later on). molecular pathways and illuminated the governments he was trying to help guide to He did his graduate work on novel quantum-mechanical evolution of atoms modernity. spectroscopies, including optically in molecules. The classic tool for him was Zewail never lost his drive to modernize detected magnetic resonance, with Robin the pump–probe experiment. Here the first science in the Arabic-speaking world. In Hochstrasser at the University of Penn- pulse (the pump) started a chemical reac- speeches and articles he reminded his coun- sylvania in Philadelphia. His postdoctoral tion, and the second (the probe) monitored trymen of the historical greatness of their work was on coherence in multidimen- what happened next. In this way he and his science, and encouraged them to build to sional systems and energy transfer in solids, team took snapshots of vibrational flow, greatness again through investment in edu- with Charles B. Harris at the University of state rearrangement and reaction prod- cation and fundamental research. He was California, Berkeley. In 1976 he joined the ucts. These revealed a much deeper role for the driving force behind the Zewail City of California Institute of Technology in Pasa- coherence than anyone had anticipated. Science and Technology in October City, dena, where he remained for the rest of his After his Nobel Prize, Zewail’s focus Giza. After a troubled gestation due to politi- career, rising to become the Linus Pauling shifted towards a new form of microscopy cal instability, this new university finally professor of chemistry in 1995. Like Pauling, that used ultrafast pulses of electrons to track opened in 2013, with institutes intended to his reputation and impact would truly reactions in space and time at the atomic cover all the fields required for development transcend science. scale. It was no secret that he hoped (like of Egyptian society. Zewail was also on US Throughout the 1980s and most of the Pauling) to win a second Nobel Prize: Zewail president Barack Obama’s Council of Advi- 1990s he led his group to do experiments on was not one to rest on his laurels. Once again, sors on Science and Technology for four years ‘femtochemistry’ — his coinage for causing truly elegant science resulted. and served as the US science envoy to the and watching reactions using light pulses Generations of talented students benefited Middle East. lasting much less than a picosecond (a mil- greatly from his insight. He longed to boil With his death, we have lost a talented lionth of a millionth of a second). This is the down complex phenomena to the simplest scientist and true statesman of the world. ■ timescale of chemical reactions at the molec- underlying dynamics. He would urge his co- ular level — the timescale of vibrations and workers to avoid getting mired in detail. A Warren S. Warren is the chair of the Physics nuclear motions. For this work he became very, very busy man, he still kept close tabs Department at Duke University, and James the sole recipient of the 1999 Nobel Prize in on his sub-basement labs. He would pop B. Duke Professor of Chemistry, Physics, Chemistry. Before the advent of such ultra- in during an experiment without warning, Radiology and Biomedical Engineering. He fast lasers in the 1970s, chemists’ ideas of the poke around, and start asking questions, was a postdoctoral fellow with Zewail from dynamics of molecules in excited states were saying he just wanted to “smell the cooking”. 1981 to 1982. very different from todays’. They believed His career and influence were shaped by e-mail: [email protected]