January 18, 2011
By the time she arrived in Berkeley, chemistry professor Naomi Ginsberg had learned some things about cold places. Born and raised in Halifax, Nova Scotia (about 400 miles northeast of Boston), Ginsberg, 32, earned her B.A.Sc. in engineering at the University of Toronto in 2000.
“The first two years of my engineering degree gave me a broad background,” says Ginsberg. “My initial interest was biomed, but I graduated with an electrical engineering focus and an emphasis on physics and optics.”
Her undergraduate summers were spent in Winnipeg and Ottawa, where she learned about nuclear magnetic resonance (NMR) imaging techniques and later studied ultrafast spectroscopy.
But it was as a Ph.D. physics student at Harvard that things really got chilly. In the research group of physics professor Lene Hau, Ginsberg studied Bose-Einstein condensates, ultracold clouds of atoms that exist at temperatures just a few billionths of a degree above absolute zero.
In an experiment that would have amazed William Giauque (1895–1982), the Berkeley chemist who received the 1949 Nobel Prize for his pioneering low-temperature studies, the Hau group halted and stored a light signal in a Bose-Einstein condensate of sodium atoms and transferred the signal into a second Bose-Einstein sodium cloud 160 microns away.
The American Institute of Physics listed this feat as #1 in its Top Ten discoveries of 2007. Ginsberg was the lead author on the paper that appeared on the cover of Nature in February of that year. Some researchers work for many years to get their first article on the cover of Nature. Ginsberg achieved that honor as a graduate student.
Although many scientists would have been content to build on such an early success, Ginsberg took a path less travelled. For her postdoc, she switched from physics to chemistry—and from ultracold systems to living ones—and chose to work with Berkeley chemist, Graham Fleming.
Fleming, the Melvin Calvin Distinguished Professor of Chemical Biodynamics, is also the campus’s research vice chancellor and a senior faculty scientist at Lawrence Berkeley National Laboratory. The Fleming group develops ultrafast spectroscopic methods to study natural photosynthetic complexes and nanoscale systems like single-walled carbon nanotubes.
When asked why she switched disciplines, Ginsberg responds, “I think new science happens when you merge different fields— it gives you a big tool box of ideas. For me, chemistry was a different vocabulary, and it took some time to get comfortable with it. I can recall the moment in my first year when Graham told me, ‘Now you are beginning to sound like a spectroscopist.’”
At the level of fundamental science, Ginsberg is seeking a broad understanding of how light and matter interact. But her quest to understand what she calls the “dynamics of very small things” is not just blue-sky research. Understanding these principles is critical for comprehending the incredible efficiency of photosynthesis and harnessing this knowledge to produce more efficient forms of solar energy.
Asks Ginsberg, “What gives rise to the remarkable efficiency of photosynthetic light harvesting? How can the energy flow be manipulated? How can this guide solar energy technologies? I want to uncover the underlying mechanisms of energy transfer by studying both natural photosynthetic systems and synthetic alternatives like photovoltaic polymers and inorganic nanostructures.”
Chromophores, the light-harvesting structures in plants and bacteria, are spaced less than a nanometer apart. Photosynthesis occurs so fast, and over such short distances, that it remains stubbornly resistant to analysis. “But by blending elements of super-resolution microscopy and ultrafast spectroscopy,” says Ginsberg, “I’d like to map the distribution of traveling photoexcitations as a function of energy, space and time.”
Ginsberg, who expresses a fondness for plants—even as she dices and blends them into a slurry for her research—has another puzzle she’d like to solve. “If you look at the arrangement of light-harvesting pigments at a molecular level,” she says, “in some bacteria they are highly ordered, while in plants the configuration is more random. Yet plants are more sophisticated. Their photosystems have control and repair mechanisms that bacteria lack.” Ginsberg adds, “Plants are like Berkeley—sophisticated, but not very orderly. I’m trying to understand the underlying mechanisms.”
As Ginsberg sets up her new lab, she doesn’t anticipate switching fields again anytime soon. Understanding the fundamental principles of photosynthesis, and helping bring about their practical application, may keep her busy for many years.