Fighting back against IEDs

December 13, 2007

A simple and inexpensive analytical technique has made it possible to detect explosives from up to 60 feet away, a desirable commodity in an age of IEDs and suicide bombers and one that may become commercially available in the near future.

The U.S. Army Research Laboratory in Maryland has developed a system that detects explosive residues, using laser induced breakdown spectroscopy (LIBS) to identify the elemental composition of molecules. Refinement and standardization of this technique would fill a growing security and military need, researchers say.

"Currently there are no proven technologies that can accomplish residue explosives detection at a distance in a real-world scenario," says Jennifer Gottfried, who led the Army research team. And though the technology still needs to be "verified and validated in real-world applications," she is optimistic they will come up with a usable device. "We expect that this technology will be available commercially very soon."

Despite a race between laboratories to perfect a commercial LIBS product, LIBS is a relatively simple spark spectrochemical technique. In order to perform LIBS one generally needs:

• Short pulse (20 nsec or faster) laser with a minimum of 10 mJ per pulse
• Optics for laser light delivery/focusing
• Optics for capturing the light emitted from the spark, and
• Spectrometer/detector to separate the light from different elements and ions for chemical identification.

LIBS works whether the sample is a solid, liquid or gas, and is sensitive to all elements, with typical limits of detection between 0.1-200 parts per million (depending on the sample and the element of interest).No sample preparation is needed making it quick and easily adaptable to automated chemical monitoring equipment or portable units.

The technique can be used in a variety of more complex analyses such as determination of alloy composition, origin of manufacture (by monitoring trace components), and molecular analysis (unknown identification). There is also the option of using LIBS as a stand-off analytical technique for corrosive or hazardous environments (such as space and nuclear reactors) preventing risk to the operator as well as for military use in man-portable or robotics applications.

SOURCES: CNET, U.S. Army Research Laboratory