Spotlight on Research: Magnetic Resonance Key to Improved Explosives Detection

Posted: October 7, 2003 at 1:00 am, Last Updated: November 30, -0001 at 12:00 am

By Lynn Burke

Assistant Professor Karen Sauer came to George Mason’s Physics and Astronomy Department in fall 2002, bringing with her a $400,000 National Science Foundation ADVANCE Fellows Award and a goal to build strong research and education programs in experimental magnetic resonance–a field that is receiving much attention these days because of the promise it holds to improve screening for explosives at airports and detecting landmines.

Sauer’s studies are focused on nuclear quadrupole resonance (NQR), a type of radio frequency spectroscopy that can help identify many substances without the use of a large static magnetic field. To illustrate the science behind NQR, Sauer cites the old Memorex commercials in which Ella Fitzgerald shatters a glass with her voice.

“She’s got to hit an exact note for the glass to break. If she hits that note, the natural resonance frequency of the glass causes the glass to break. If she hits other notes, it won’t. It’s the same thing with this technology. You send out what’s basically a very particular radio frequency wave that’s known as the resonance frequency of the material,” says Sauer. “If you actually hit something with a corresponding resonance frequency, then it will actually resonate. Basically, the nuclei start reorienting themselves and start clicking back and forth in response to that radio frequency. We listen for that response.”

According to the Naval Research Lab, where Sauer first became involved in this research while doing postdoctoral work, because NQR frequencies are highly specific to chemical structure, signals from other nitrogenous materials would not interfere with the detection of explosives, which would help eliminate false alarms. Other benefits include shortened inspection time for luggage, safe screening of magnetic media, and low radio frequency field strengths so that long-term exposure would not harm airport workers and may possibly allow the technology to be used directly on people.

Sauer says the technology is starting to be commercialized by a company called Quantum Magnetics and can be found in airport baggage scanners and backpacks that soldiers use to detect landmines. “But a lot of work still needs to be done on the research end,” she says, adding that as the technology is introduced into the field and gains more practical applications, questions arise. “You have to go back to your research and try to answer them,” she says. Despite the problems, Sauer believes the technology holds great promise for the future.

Her work in nuclear quadrupole resonance was recently bolstered by a Ralph E. Powe Junior Faculty Enhancement Award given by the Oak Ridge Associated Universities to George Mason on her behalf. George Mason will match the $5,000 award, which will go toward hiring a graduate student to help with the research.

Prior to coming to George Mason, Sauer was a National Research Council Postdoctoral Fellow at the Naval Research Lab, and prior to that, she was a Chateaubriand Postdoctoral Fellow at Ecole Normale Superieure in Paris for two years.

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