Nobel Prize winner dazzles audience with chemical 'snapshots'

Zewail packs house for Evans lecture

Hundreds of University faculty, staff and students crowded into a lecture hall in McPherson Laboratory Oct. 27 to hear Ahmed Zewail, 1999 Nobel Prize winner in chemistry, deliver this year's William Lloyd Evans Lecture.

Visitors lined the aisles and stood on tiptoe in the back of the crowd to catch a glimpse of the event, hosted by the Department of Chemistry.

Zewail, a professor of chemistry and physics at the California Institute of Technology, detailed his technique for viewing ultra-fast chemical reactions. Such reactions are so fast they last for a femtosecond, or one quadrillionth of a second.

Knowing what is happening inside molecules during this critical time may unlock mysteries in chemistry, biology and medicine.

"Professor Zewail's development of femtochemistry has provided chemists with unprecedented 'snapshots' of what happens during chemical reactions," said Bruce Bursten, chair of the Department of Chemistry. "His research has literally changed the way we view the progress of fundamental chemical reactions."

"Just like the starting gun that begins a race and the tape at the finish line, Ahmed Zewail's technique uses one ultrashort burst of light to start a chemical reaction and then another burst of light to time when the products appear. For a chemical reaction, the whole race is run in a matter of a few femtoseconds," explained Sherwin Singer, associate professor of chemistry.

Zewail will continue to explore the possibilities of this technology with his colleagues at Caltech. "I have to tell you, I'm not retiring," he said at the beginning of his lecture. "We have a long way to go."

"I am very impressed that Professor Zewail is now embarking on a major new effort to replace that second burst of light with a burst of electrons," said Singer. "This generates an electron diffraction pattern which provides a snapshot of atomic position even when the reaction products do not respond to light pulses.

"The electron diffraction method, if successful, will open a much wider class of molecules for study, including large biological molecules."

The Evans Lecture series was established in 1961 in recognition of the late William Lloyd Evans for his distinguished service to the Department of Chemistry. Evans was an alumnus, professor and former chair of the department who retired in 1941 but continued his work in chemistry until his death in 1954. Each year since it established the award, the department has selected a chemist of outstanding international stature to deliver the annual lecture.

"The Department of Chemistry is proud of our tradition of excellence in bringing the most eminent chemists throughout the world to be our Evans lecturers," said Bursten. "The Evans lectures are always an energizing time in our department.

"Our undergraduate and graduate students are justifiably thrilled at the opportunity to hear from and talk with these famous researchers."

The Department of Chemistry scheduled Zewail for the event nearly one year ago, and he received his Nobel on Oct. 12 -- about two weeks before the lecture.

This isn't the first time a chemist has received the Nobel Prize shortly before or after giving an Evans Lecture. In 1996, Richard Smalley of Rice University received his Nobel only one day before his lecture.

In fact, Singer pointed out that the Department has developed a knack for scheduling chemists who are just about to win the prize. "Every year we get more bargaining power with potential speakers," he said, and smiled.

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