Tunable infrared laser detection of pyrolysis products of explosives in soils

Wormhoudt, J.; Shorter, J. H.; McManus, J. Barry; Kebabian, Paul L.; Zahniser, M. S.; Davis, Wendy; Cespedes, Ernesto R.; Kolb, C. E.

doi:10.1364/ao.35.003992

Cited by 24 publications

(9 citation statements)

References 9 publications

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“…We note here that the current technique of detecting soil contamination by energetic materials also relies on fragmentation (78,135,136). A cone penetrometer probe is driven into the ground with a heated section that carries out the thermal decomposition.…”

Section: Fragmentation and Fragment Detectionmentioning

confidence: 99%

EXPLOSIVES DETECTION: A Challenge for Physical Chemistry

Steinfeld

Wormhoudt

1998

Annu. Rev. Phys. Chem.

398

242

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The detection of explosives, energetic materials, and their associated compounds for security screening, demining, detection of unexploded ordnance, and pollution monitoring is an active area of research. A wide variety of detection methods and an even wider range of physical chemistry issues are involved in this very challenging area. This review focuses on techniques such as optical and mass spectrometry and chromatography for detection of trace amounts of explosives with short response times. We also review techniques for detecting the decomposition fragments of these materials. Molecular data for explosive compounds are reviewed where available.

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Section: Fragmentation and Fragment Detectionmentioning

confidence: 99%

EXPLOSIVES DETECTION: A Challenge for Physical Chemistry

Steinfeld

Wormhoudt

1998

Annu. Rev. Phys. Chem.

398

242

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“…Laser-based sensors are being developed in the laboratory which can be incorporated into a SCAPS probe. Previously in this article, we have described the detection of explosive pyrolysis products from soil detected by TILDAS (38) (Figure 2 and Table 3) and the detection of TNT in soil by PF/LIF spectroscopy (134 -136) (Figure 12 and Table 6). In the following paragraphs, some of the applications of SCAPS for explosives detection for environmental application along with analytical methods are discussed.…”

Section: Environmental Applicationsmentioning

confidence: 97%

“…Thus, IR spectroscopy is a good confirmatory test if sufficient quantity of sample is available. Wormhoudt et al (38) have reported their efforts to develop a tunable infrared laser differential absorption spectroscopy (TILDAS) system for in situ identification of the presence of explosives in subsurface soil. (39) In laboratory tests, a 900°C pyrolyzer ring heater was placed a short distance (about 0.25 cm) from the soil surface and the soil was heated for periods of the order of minutes.…”

Section: Tunable Infrared Laser Differential Absorption Spectroscopy mentioning

confidence: 99%

Laser‐ and Optical‐Based Techniques for the Detection of ExplosivesUpdate based on the original article by David L. Monts, Jagdish P. Singh and Gary M. Boudreaux,Encyclopedia of Analytical Chemistry, © 2000, John Wiley & Sons, Ltd

Hummel

Dubroca

2013

Encyclopedia of Analytical Chemistry

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A wide variety of optical‐ and laser‐based techniques have been and are currently being investigated as means of identifying and characterizing explosive materials. These efforts are hampered by the very low volatility of explosive compounds at room temperature and their tendency to ignite at higher temperatures where their vapor pressures are beginning to reach a regime where the species can be readily detected. Traditional, condensed‐phase absorption spectroscopy (both infrared (IR) and ultraviolet/ visible (UV/VIS)) requires larger samples than are frequently available and, although useful as confirmatory techniques, do not provide signatures that enable unique identification of species. The choice of nontraditional techniques for analysis of explosive materials is dependent upon the amount of sample available, the sample matrix, and sample‐imposed constraints upon the measurement. Raman spectroscopy can identify and quantify condensed phase explosive materials, but the detection limit depends upon substrate, excitation wavelength, and illumination area: limits of detection (LODs) vary from 0.05 ng for 2,4,6‐trinitrotoluene (TNT) on glass to 10 µg for nitroglycerin (NG) on silica gel. The other detection techniques considered require volatilization of either the explosive compound itself or more often of characteristic decomposition products, such as NO, NO 2 , or N 2 O. Using IR irradiation, researchers have demonstrated that photoacoustic spectroscopy (PAS) has detection limits ranging from 0.55 ppb (parts per billion) for vapor‐phase NG with 9 mm excitation to 220 ppm (parts per million) for vaporphase 2,4‐dinitrotoluene (DNT) with 6‐µm excitation. IR laser differential absorption detection of dissociation products NO, NO 2 , and/or N 2 O can achieve detection limits of a few picograms. Laser‐induced fluorescence (LIF) detection of the photofragments (typically NO) of explosive compounds yields detection limits in the tens to hundreds of ppb (by weight) range. Low LODs can be achieved using ion detection techniques: resonance‐enhanced multiphoton ionization (REMPI) spectrometry is capable of LODs for detecting vapor‐phase explosives compounds in the hundredths to tens of ppb range; ion mobility spectrometry (IMS) has vapor‐phase detection limits for common explosive compounds of typically 200 pg, but for some species can be significantly lower: for example, 1 pg for TNT.

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“…Explosives represent only one area of concern, as the same sensing technology could be easily adaptable to the general class of threat agents that includes nuclear, biological, and environmental toxins. The ideal detection system for threat agents, whether these threats are explosives, chemical and biological agents, or illicit drugs, would possess high sensitivity (i.e., be capable of detecting threats present only at trace levels), be able to discern a threat amidst a real world background, possess a standoff capability, be straightforward to operate, and possess a real time sensing potential [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. This last operational criterion will be critical whether the sensor is deployed at a military checkpoint, for airport security, or for any other domestic application where impeding the flow of commerce is an issue.…”

Section: Introductionmentioning

confidence: 99%

Standoff Methods for the Detection of Threat Agents: A Review of Several Promising Laser-Based Techniques

Johnson¹,

Allen²,

Merten³

et al. 2014

Journal of Spectroscopy

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Detection of explosives, explosive precursors, or other threat agents presents a number of technological challenges for optical sensing methods. Certainly detecting trace levels of threat agents against a complex background is chief among these challenges; however, the related issues of multiple target distances (from standoff to proximity) and sampling time scales (from passive mines to rapid rate of march convoy protection) for different applications make it unlikely that a single technique will be ideal for all sensing situations. A number of methods for spanning the range of optical sensor technologies exist which, when integrated, could produce a fused sensor system possessing a high level of sensitivity to threat agents and a moderate standoff real-time capability appropriate for portal screening of personnel or vehicles. In this work, we focus on several promising, and potentially synergistic, laser-based methods for sensing threat agents. For each method, we have briefly outlined the technique and report on the current level of capability.

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Tunable infrared laser detection of pyrolysis products of explosives in soils

Cited by 24 publications

References 9 publications

EXPLOSIVES DETECTION: A Challenge for Physical Chemistry

EXPLOSIVES DETECTION: A Challenge for Physical Chemistry

Laser‐ and Optical‐Based Techniques for the Detection of ExplosivesUpdate based on the original article by David L. Monts, Jagdish P. Singh and Gary M. Boudreaux,Encyclopedia of Analytical Chemistry, © 2000, John Wiley & Sons, Ltd

Standoff Methods for the Detection of Threat Agents: A Review of Several Promising Laser-Based Techniques

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