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Laser-based micro-spectrochemical analysis in forensic and security applications
Prof. José R. Almirall
Department of Chemistry and Biochemistry and International Forensic Research Institute
Florida International University, Miami FL USA
www.ifri.fiu.edu
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Analytical Chemistry with LIBS
sample is ablated by pulsed laser beam with sufficient energy to excite/ionize the material = breakdown thresholdtypically peak power energies of 10-100 mJ/pulse
are focused to an intensity of 1010-1012 W/cm2
Nd:YAG laser (1064 nm, 8 ns)
spectrometer
Laser-Induced Breakdown
Spectroscopy
Courtesy of the Army Research Laboratory
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Advantages of LIBS for Materials Detection and Identification
• Real-time, true standoff detection capability– conventional nanosecond LIBS has been demonstrated at
distances >100 meters, residue explosives at 50 meters• No sample preparation required, single-shot analysis of residues has
been demonstrated• High Sensitivity (ng), High Specificity (typically >95% True Positives,
<5% False Positives, when using advanced chemometrics)• Elemental Fingerprinting (broadband high resolution spectrometer
capable of detecting most elements on periodic table in each laser shot) • LIBS provides universal materials detection/characterization• LIBS works on various states of unknown materials- solids/residues,
liquids, aerosols, vapors.
Courtesy of the Army Research Laboratory
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LIBS Sensor Suite & Applications
LIBS Probe for Humanitarian Demining
THREATDETECTED
Standoff detection
MP-LIBS
Underwater
Navy Ships- 300 m standoff
Suitcase LIBS “Lab-in-Field”
Spectrometer
Remote/Fiber-Optic LIBS
Robo-LIBSOptics
Data Processing
0
500
1000
1500
2000
2500
3000
200 400 600 800
Wavelength (nm)
Inte
nsity
(a.u
.)
Laser
Courtesy of the Army Research Laboratory
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Typical LIBS Spectra of Explosives
Single-shot double pulse standoff (30 m) spectra of explosive residues on aluminum
Courtesy of the Army Research Laboratory
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Explosive-containing Mixtures, 25 meters, double pulse
Threshold
Courtesy of the Army Research Laboratory
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Maryland Attempted Bank Robbery
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Glass is evidence of association – LIBS Analysis
8
Association between fragments in a bank robbery case –confirmed by LA-ICP-MS
266 nm laser
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CSI, Las Vegas episode: “What’s eating Gil Grisham”
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Acknowledgements• Almirall research group
Dr. Benjamin NaesTatiana TrejosErica CahoonSarah JantziEmily SchenkAlejandra Flores (IUPUI)
• National Institute of Justice for funding LIBS research (2005-IJ-CX-K069)
•
• Army Research Office - STIR grant for LIBS research
• Dr. Andrzej Miziolek of the Army Research Laboratory, APG
• American Chemical Society and Optical Society of America