Issue Date: February 23, 2009
Ahmed Zewail Award in Ultrafast Science & Technology
Sponsored by the Ahmed Zewail Endowment Fund established by Newport Corp.
Appropriately, the joint winners of this year’s award met in a graduate-level lasers class. It was in that idyllic, romantic setting at the University of California, Berkeley, that Henry C. Kapteyn and Margaret M. Murnane began both a successful personal relationship, which eventually led to marriage, and a fruitful professional relationship, which has resulted in a number of important scientific and technological advances in the field of ultrafast science.
Collaboration, in fact, has been the key to their success, Murnane and Kapteyn say. They were the first two grad students to join Roger Falcone’s research group at UC Berkeley, and at the time, colleagues said that was a bad idea, Murnane says. People thought that being in the same field would make it difficult for spouses to find faculty positions together, she explains. But “we turned what people told us was a disadvantage into an advantage. We decided that if we worked together, we could compete with other very large groups throughout the world,” she says.
Kapteyn and Murnane each received a Ph.D. from UC Berkeley in 1989 and proved the skeptics wrong, taking their “whole is greater than the sum of its parts” philosophy with them to Washington State University, where they both had received faculty appointments in the department of physics. Once there, Kapteyn says, they had to start from scratch and build their own joint lab. “So we decided that we really should look into the latest technologies,” he says. For the pair, that meant a new generation of ultrafast lasers.
One that caught their attention was the first mode-locked Ti:sapphire laser, developed in 1990 by Wilson Sibbett of the University of St. Andrews, in Scotland. But its pulse duration was limited at 60 femtoseconds, “much longer than one might theoretically expect,” Murnane points out. She and Kapteyn made it their mission to understand why.
After considerable theoretical and experimental work optimizing the laser’s design, the duo and their graduate students built a laser with a shorter pulse duration of 10 fs that was significantly more stable. “What we found was that when we made the pulses shorter, it made the technology more reliable and more powerful,” Kapteyn says. At that time, reaction from scientists in the field was mixed: Some didn’t think a 10-fs pulse could possibly be useful for anything, whereas others were excited and asked for drawings of the laser design so that they could duplicate it.
Murnane and Kapteyn, ever the team players, quickly provided their designs to hundreds of labs worldwide, thereby driving the revolution in ultrafast laser technology. Because of the widespread demand for their design, the couple eventually began selling laser kits to nonexperts and those who simply didn’t have the facilities to build their own parts. And after submitting their tenure packages in 1994, they started their own company, Kapteyn-Murnane Laboratories, or KMLabs, which is now based in Boulder, Colo.
“This effort cannot be underestimated,” says Rick Trebino, chair of the ultrafast optical physics department at Georgia Institute of Technology. “It made available to the scientific community this technology at a very reasonable price, allowing much excellent research to occur at less well-funded labs that might not otherwise have occurred. Indeed, I currently own three of their lasers.”
After developing the 10-fs laser at Washington State, the couple continued to lead the charge in ultrafast technology. They demonstrated the first sub-10-fs laser and also combined their intense ultrashort pulses with nonlinear optical techniques to generate coherent X-rays. To do the latter, Murnane and Kapteyn achieved high-order harmonic generation in a hollow-core fiber, thereby developing the first general technique for efficiently converting visible laser light into coherent extreme ultraviolet and X-ray light. “Our objective all the way from the beginning was to make coherent, ultra-short-duration, X-ray pulses,” Kapteyn says, pointing out the progression of their work.
And today they are using those pulses to access some of the fastest processes in nature—including electron dynamics on the attosecond timescale—establishing themselves as pioneers in yet another area of science. The technology has allowed us “to really begin to look at the coupled motion of electrons and atoms in molecules or the correlated motion of electrons in solids,” Murnane explains.
Kapteyn, 46, received a bachelor’s degree in physics from Harvey Mudd College, in Claremont, Calif., in 1982 and a master’s degree, also in physics, from Princeton University in 1984. Murnane, 50, received both bachelor’s and master’s degrees in physics from the University College Cork, in Ireland, in 1981 and 1983, respectively. After starting out as assistant professors at Washington State, they moved their joint lab to the University of Michigan, Ann Arbor, and then to the University of Colorado, Boulder, where they currently teach and do research as part of JILA, an institute jointly operated with the National Institute of Standards & Technology.
The couple’s work, in well over 160 papers, has been cited more than 7,500 times. They have each been recognized with numerous awards. Among them are Murnane’s 2000 MacArthur Fellowship and Kapteyn’s 1993 Adolph Lomb Medal of the Optical Society of America.
But this is the first joint award for the duo, and as such, it means a lot, they say. It also holds special meaning, coming from ACS, Murnane says. “We’ve been collaborating with chemists since 1991,” she explains. “A lot of the people who saw the promise of the femtosecond and attosecond science and technology from the beginning were chemists.”
Kapteyn and Murnane will present the award address before the Division of Physical Chemistry.
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