Physicist Marlan Scully from Texas A&M has led a team of researchers to make a breakthrough in the use of lasers for the rapid and accurate identification of biological samples.
“Our report shows how to use lasers to detect anthrax in real time as opposed to the cumbersome and wieldy way it is done now,” says Marlan Scully, Distinguished Professor of Physics at Texas A&M. “We do our experiments ‘on the fly’, so we can get a signature within a tiny fraction of a second. Our procedure can work for monitoring anthrax in mail, but it can also scan the whole atmosphere. And there are a lot of other potential applications — monitoring glucose in the blood, for example.”
The new technique is based on coherent anti-Stokes Raman scattering (CARS), a phenomenon that measures the light scattering that occurs when a molecule is bombarded by light energy (photons). Molecules are composed of two or more atoms, and the subatomic particles which make up these atoms are in constant motion, producing vibration patterns unique to each substance. When a molecule is hit by an appropriate sequence of laser pulses, it gives off light in a specific ‘fingerprint’ pattern. If three laser pulses are used, the resultant emitted light yields a coherent signature at a particular frequency.
“This paper is a remarkable achievement in that it makes very clever use of modern techniques for coherent control to detect molecular signals with high sensitivity. Many important practical applications can be foreseen for this technology,” says Harvard professor of physics Mikhail Lukin.