Prof. Dr. Ahmed H. Zewail > Research Profile
By Mariam Elbaz
For most of the history of chemistry, scientists could only infer how a reaction happened. The molecules could be seen before or after a reaction, but the instant in which a chemical bond broke or formed was invisible. As Nobel Laureate Ahmed H. Zewail explained in his 2002 lecture at the 52ⁿᵈ Lindau Nobel Laureate Meeting, if an experiment averages over time, "you would not see any motion, you just simply see a probability over all distances." His insight was that motion only becomes visible once the time interval used to observe it is made short enough. By shrinking that interval down to the femtosecond, one million billionth of a second, Zewail found a way to "clock" the actual movement of atoms as a reaction unfolded. This achievement, which came to be known as Femtochemistry, earned him the sole Nobel Prize in Chemistry in 1999. It is worth noting that he is the first Egyptian to receive a Nobel Prize in Chemistry. His scientific legacy included more than 700 publications contributing to bridging the gap between atomic research and biological systems. From 2009 to 2013, Zewail served as the first U.S. Science Envoy to the Middle East under President Obama. Ahmed Zewail passed away on August 2ⁿᵈ, 2016, after a fight with cancer. His journey from a small Egyptian town to the Nobel stage, and later to science diplomacy, was winding.
Long before he earned the title, his family had already placed a sign reading "Dr. Ahmed" on his study door, an expression of the ambition they held for him. Ahmed Hassan Zewail was born on 26 February 1946 in Damanhour, Egypt, and grew up in the nearby town of Desouk, on the banks of the Rosetta branch of the Nile. He received his early education in Egyptian state schools before being admitted to the Faculty of Science at Alexandria University. In his second year, he scored very highly in chemistry and was selected for an elite group of chemistry students. He completed his Bachelor of Science degree in 1967 and started teaching as a demonstrator. He then completed his master’s degree in 1969 in the field of spectroscopy. It was during these years that his lifelong fascination with natural phenomena began to take shape.
Several of his professors at Alexandria recognized his talent and pushed him toward more ambitious goals. Professors Samir El Ezaby (a graduate of Utah) and Yehia El Tantawy (a graduate of Penn) in particular encouraged him to pursue his doctorate in the United States. Convinced this was the right path, Zewail spent considerable time and effort searching for an American university willing to sponsor his postgraduate education. It was not a small task, since most Egyptian students of that era went to the Soviet Union or Eastern Europe rather than the US. His persistence paid off when the University of Pennsylvania offered him a scholarship. Even then, the path was not simple: The fellowship offer letter could not name him directly due to Egyptian government restrictions, which meant every other honours student first had to turn it down before he could be confirmed as the sole candidate. Only days before he was due to leave, he finally managed to collect the necessary signatures to make his departure possible.
When Zewail arrived in the United States to begin his doctoral studies at the University of Pennsylvania, he stepped into an entirely new world: a new culture, a new language, and, compared to Egypt, an almost unlimited access to scientific resources and equipment. He completed his PhD in 1974 under the supervision of Robin Hochstrasser. Zewail published ten papers with Hochstrasser. Most focused on the high-resolution spectroscopy of triplet states. For these experiments, molecules were cooled below 2 Kelvin inside glassy substrates. A xenon lamp usually provided the excitation. One paper, though, used a custom-built laser instead.
Mentorship continued to shape his path in America just as it had in Egypt. In 1974, he joined the research group of Charles B. Harris at the University of California, Berkeley, for a postdoctoral fellowship. Berkeley, he later said, was a place for 'the BIG science.' There, he continued the high-resolution spectroscopy work he had started at Penn, studying molecules at low temperatures using similar methods. But his focus expanded to a new problem: the coherence between pairs of molecules called dimers, and how energy could move coherently through solids. Harris was away in Holland for much of this time, but when he returned, the two spent late nights deep in scientific discussion. Zewail decided to tackle the coherence problem himself. In a short time, he built a rigorous theoretical foundation, which he later called vital to his future research. His work also led to frequent conversations with Professor Alex Pines, a leader in nuclear magnetic resonance spectroscopy at Berkeley. Later Zewail and Harris co-authored two papers, one theoretical and one experimental , both published in Physical Review. Zewail then extended the concept of coherence to multidimensional systems, publishing his first paper as sole author. Beyond science, Zewail and Harris bonded over their shared Middle Eastern roots, and Harris became another mentor Zewail could turn to, both for science and for guidance on his future. It was Harris who eventually helped him secure a faculty position at a top university, one that would give him access to cutting-edge research and the best students.
In 1976, Zewail joined the California Institute of Technology as an assistant professor, and he would remain there for the rest of his career, becoming a full professor by 1982. Caltech was a place defined not only by scientific rigor but by a striking diversity of people and disciplines. Zewail describes himself as a people person, someone who could read a room and connect easily with colleagues from very different backgrounds, and this ability served him well in an institution that thrived on collaboration across fields. It was in Caltech, over the following decade, where Zewail assembled the laser techniques and the research group that would make femtochemistry possible. With limited startup funds, he leased and borrowed lasers to build his lab yet published one paper in his first year and eight in his second, an unusual pace for a new laboratory built from scratch. His early work centred on coherence and energy transfer between molecules, and by 1979 his lab could generate laser pulses as short as 0.66 picoseconds. A pivotal shift came in 1980, when physicist Richard Bernstein urged him to focus entirely on the fundamentals of ultrafast lasers and chemistry, advice that set the direction for the next phase of his career. The breakthrough came in 1987, when Zewail's group achieved the first direct observation of a transition state during a chemical reaction, capturing the photodissociation of the ICN molecule using ultrafast laser pulses lasting only 200 femtoseconds. For the first time, researchers could watch a chemical bond break in real time rather than simply comparing the molecule before and after the reaction.
This body of work, built up over more than a decade, earned Ahmed Zewail the Nobel Prize in Chemistry in 1999. As he later described the moment, when the Swedish Academy called to tell him he had won, he knew that he "would not have peace after that." By then he had already transformed how chemists thought about molecular motion, yet he continued to see, in his own words, millions of further possibilities still waiting to be explored. Rather than slow down after the Nobel Prize, Zewail responded with what colleagues described as the energy of a young assistant professor. He set his sights on an even bolder goal: bringing his molecular-movie techniques to biology itself, hoping, in his words, 'to be able to see the machinery of life in action.' Building on the foundation of ultrafast electron diffraction, he pioneered four-dimensional electron microscopy (4D UEM), combining the fine spatial resolution of electron microscopy with femtosecond-scale timing. He envisioned using 4D UEM to study everything from nanocrystals and surfaces to self-assembling structures, and ultimately to image a living cell. This goal was supported by an $18 million grant from the Gordon and Betty Moore Foundation in 2005. Along the way, his group also contributed insights into the dynamics of water in biological recognition, carrying femtochemistry deeper into the workings of living systems. All of this came alongside an extraordinary workload: leading a large research group, serving as editor of Chemical Physics Letters, publishing an average of twenty scientific papers a year, teaching, and delivering more than twenty invited lectures annually. Yet Zewail felt he could do even more for the world beyond the laboratory. Two concerns increasingly occupied him: unimpeded scientific freedom and universal access to education. Two themes he saw as deeply connected, since he believed that freedom of thought and expression was essential to both good science and a peaceful society. He believed that education was the surest path to lifting people out of poverty.
Zewail increasingly came to believe that his responsibility extended beyond femtochemistry and into the broader relationship between science and society, particularly in the region he came from. That belief would soon take him from the lab bench to the world stage. Zewail became one of the most visible practitioners of Science Diplomacy when the Obama administration appointed him the United States' Science Envoy to the Middle East. In this role, he took on the responsibility of using his scientific standing to influence international relations across the Middle East and North Africa. He positioned himself as an advocate for peace, education, and scientific funding across the region. Alongside this diplomatic work, Zewail pursued a long-held ambition to build a science and technology hub for Egyptian students, founding what became known as Zewail City of Science and Technology in Egypt, intended to cultivate a new generation of Egyptian scientists.
In June 2013, Zewail disclosed that he was being treated for a cancerous tumor of the spinal cord. Despite his illness, he remained publicly active, continuing to give keynote lectures internationally. At a 2015 address at UNESCO's celebration of the International Year of Light, he joked that 'sometimes people think that after the Nobel Prize you could sleep' before describing new work using electron microscopy to study everything from nanoscale machines to Alzheimer's-linked proteins. Ahmed Zewail died on 2 August 2016 at his home near Pasadena, California, at the age of 70. His body was returned to Egypt, where a military funeral was held on 7 August 2016 in Cairo. He was buried in Egypt, honouring what his family described as his wish to rest in his home country. He was survived by his wife, Dema Faham, and his four children, Maha, Amani, Nabeel, and Hani. Over the course of his career, Zewail was honoured with dozens of prizes and distinctions, including the King Faisal International Prize (1989), the Wolf Prize in Chemistry (1993), the Franklin Medal (1998), the Nobel Prize in Chemistry (1999), the Priestley Medal (2011), and the Davy Medal (2011). He was elected to the U.S. National Academy of Sciences, the Royal Society of London, the American Philosophical Society, and academies in Sweden, Russia, China, and France, and received honorary degrees from roughly forty universities worldwide. Egypt and several other nations also recognized him with state honours, including the Grand Collar of the Order of the Nile and France's Legion of Honor. Together, these honours reflect a scientific legacy that reshaped chemistry, and a personal legacy rooted in his commitment to science, education, and Egypt.
Sources:
Dantus, M. (2021). Ahmed Zewail, 1946–2016: A biographical memoir. National Academy of Sciences. https://www.nasonline.org/wp-content/uploads/2024/10/Zewail_Ahmed.pdf
Pankevich, D. (2016, August 5). Dr. Ahmed Zewail (1946–2016). Obama White House Archives. https://obamawhitehouse.archives.gov/blog/2016/08/05/dr-ahmed-zewail-1946-2016/
Thomas, J. M. (2020). Ahmed Hassan Zewail. 26 February 1946–2 August 2016. Biographical Memoirs of Fellows of the Royal Society, 68. https://doi.org/10.1098/rsbm.2019.0040
Zewail, A. H. (1975). Coherence in the excited states of multidimensional systems: Dimer and exciton dynamics in crystalline phenazine. Chemical Physics Letters, 33(1), 46–52.
Zewail, A. H. (1999). Ahmed Zewail – Biographical. NobelPrize.org. Nobel Prize Outreach. https://www.nobelprize.org/prizes/chemistry/1999/zewail/biographical/
Zewail, A. H. (2000). Femtochemistry: Past, present, and future. Pure and Applied Chemistry, 72(12), 2219–2231. https://doi.org/10.1351/pac200072122219
Zewail, A. H., & Harris, C. B. (1975). Coherence in electronically excited dimers. Chemical Physics Letters.
Zewail, A. H., & Harris, C. B. (1975). Coherence in electronically excited dimers. II. Theory and its relationship to exciton dynamics. Physical Review B, 11(2), 935.