Ultimately, this light-pulse research could help remove one of the last barriers preventing scientists from understanding the microscopic processes underlying daily existence and allow researchers to record the motion of electrons as they move inside atoms and semiconductors. In turn, this would open up a new window on processes like chemical bonding and electrical conductivity, which could prove valuable in the production of "designer molecules" by the pharmaceutical industry or extremely fast electronic circuits.
For her work on this area of atomic and optical physics, LSU Assistant Professor of Physics and Astronomy Mette B. Gaarde has been selected to receive a National Science Foundation CAREER Award. The NSF CAREER Award is the Foundation's most prestigious award for junior faculty members. It is part of the Faculty Early Career Development (CAREER) Program, which "recognizes and supports the early career-development activities of those teacher-scholars who are most likely to become the academic leaders of the 21st century." CAREER Award recipients are selected on the basis of creative career-development plans that effectively integrate research and education within the context of the missions of their institutions.
The CAREER Award involves grant support of close to a half million dollars over a five-year period. Gaarde's award grant will be effective June 1 of next year. She was selected for her work on so-called "attosecond" pulses of light, as well as an educational component that involves enhancing secondary education teacher preparation in physics.
Attosecond pulses are produced in the interaction between intense, ultra-short laser pulses and atoms in the gas phase. One attosecond is one billionth of a billionth of a second.
Essentially, these pulses – the shortest pulses of light ever produced – act almost like an ultra-fast strobe light, capturing "snapshot" looks at electrons in the act of rearranging themselves during events such as chemical bonding. For her research in this area, Gaarde is actively collaborating with three experimental groups: one at Ohio State University; one in Lund, Sweden; and another in Zurich, Switzerland.
"In the history of science, great advances have often come as a result of breaking barriers in the time domain," said Gaarde. "Our understanding of biological processes, surface chemistry and molecular dynamics have all been aided by the development of ever-shorter pulses of light."
Gaarde explained that, in order to study an event – such as electron rearrangement – unfolding in time, it is necessary to probe its status several times during its evolution.
"As an example, when an apple falls from a tree and on to the ground, we can visually probe that process because we can see – and our brains can process – the path the apple follows as it is falling," she said. "We could also film the process with a camera and, if the shutter speed was fast enough, the different still pictures would show the apple in different heights over the ground as it was making its way down. What this simple example illustrates is that the probe of the evolution of a time-dependent process needs to be significantly shorter than the process itself."
Thus, she said, using attosecond pulses of light, researchers can study the evolution of events that unfold on a minuscule time scale. In addition to the research, Gaarde's plans for her CAREER Award grant include an educational effort. She will work to help LSU develop "rigorous, content-based physics courses for secondary education teachers" in order to "better qualify them for teaching physics in grades 6-12."
For more information on the research or grant, contact Gaarde at 225-578-0889 or gaarde@phys.lsu.edu.