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U.S. Army Research Laboratory

Metrology

U.S. Army Researchers Explore Laser Detection Techniques

LIBS technology to help in difficult chemical analyses

Published: Wednesday, June 9, 2010 - 06:00

(U.S. Army Research Laboratory: Adelphi, MD) -- As the need for chemical, biological, and explosive detection becomes more relevant in today’s world, the U.S. Army Research Laboratory (ARL) is leading the effort in laser-induced breakdown spectroscopy (LIBS), which is capable of highly advanced materials analysis.

The technology has shown significant advancements since its inception during the 1980s. Today, LIBS technology is used for multiple purposes, including the 2011 mission to Mars; detection of chemical, biological, radiological, nuclear, and explosive material; and materials matching in forensic cases.

Andrzej Miziolek, Ph.D., and his collaborators in the ARL’s Advanced Weapons Concepts Branch are at the forefront of standoff detection pertaining to trace amounts of hazardous materials using the LIBS technology. Their work is an important example of applying spectroscopy to difficult problems in chemical analysis.

“One of the many reasons LIBS is so successful is because it combines laser ablation with sample excitation, all in a single laser shot,” says Miziolek. “We have the capability to remove nanograms of material from the surface, whether the material is bulk or a residue. The resultant microplasma emits light, which is analyzed by a spectrometer.

“The ARL has led the evolution of a new generation of LIBS, where we combine single-shot spectrum capture with advanced signal processing to identify the material,” adds Miziolek. “Thus, we analyze each spectrum on the fly, rather than average many spectra. We have one shot to get it right; once the residue is gone, it is gone.”

In 2000, the ARL worked with Ocean Optics Inc. to develop a new capability—a broadband high-resolution spectrometer which was commercialized in 2003. This new spectrometer allows the LIBS system to be sensitive to all chemical elements in the periodic table, as long as their concentration is parts per million or higher within the sample. This makes LIBS a very general tool for materials analysis, both benign and hazardous.

According to Miziolek, the LIBS system has the ability to detect all five of the threats in chemical, biological, radiological, nuclear, and high-yield explosives (CBRNE), as long as the laser hits the materials directly. “As recently as a decade ago, very few people would have expected that LIBS, which is fundamentally an elemental analysis technology, would be able to identify unknowns of biological origin, let alone to be able to differentiate between pathogenic and nonpathogenic strains of the same bacterium,” Miziolek notes.

Although commercializing this technology for field applications is a slow process in the United States, LIBS has grown substantially in Europe. Miziolek serves as a subject matter expert in “standoff LIBS” in many areas locally and worldwide. A recent advance was his efforts in getting LIBS accepted to the Standardized Equipment List, which is an important step in transferring technology from lab to user through the commercialization process.

The ARL LIBS group includes Frank DeLucia, Chase Munson, and Jennifer Gottfried, all of whom have been instrumental in generating the data that show consistent analytical success of 95-percent true positives. They have also pioneered the use of advanced chemometrics, and their work has been adopted by many other LIBS laboratories worldwide.

“The best is yet to come with LIBS, with the anticipated commercialization of rugged and user-friendly field devices in many different form factors, including standoff, close-contact, robotic-mounted, and underwater systems,” says Miziolek.

The attributes of LIBS are compelling and include real-time analysis, no sample preparation, high sensitivity, and high specificity. The recent development of real-time signal processing software has made one-second analysis a reality.

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U.S. Army Research Laboratory

The U.S. Army Research Laboratory (ARL) of the U.S. Army Research Development and Engineering Command (RDECOM) is the Army’s corporate, or central, laboratory. Its diverse assortment of unique facilities and dedicated work force of government and private sector partners make up the largest source of world-class integrated research and analysis in the Army.