Quantitative infrared spectra of vapor phase chemical agents

Sharpe, Steven W.; Johnson, Timothy J.; Chu, Pamela M.; Kleimeyer, James A.; Rowland, Brad

doi:10.1117/12.487073

Cited by 31 publications

(21 citation statements)

References 5 publications

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“…The tests made with DMMP can be used to estimate with good accuracy the performance of the system against Sarin and other nerve agents of the G and V classes. Since the strength (alpha) and position (lambda max) of the absorption peaks are so close for DMMP (α DMMP = 2.7 • 10 −3 ppm −1 m −1 at the wavelength λ = 9.52 μm [7]) and Sarin (α Sarin = 3.0 • 10 −3 ppm −1 m −1 at the wavelength λ = 9.88 μm [8]), the LoD for Sarin can be calculated as…”

Section: Discussionmentioning

confidence: 99%

Chemical Warfare Agents Analyzer Based on Low Cost, Room Temperature, and Infrared Microbolometer Smart Sensors

Corsi

Dundee

Laurenzi

et al. 2012

Advances in Optical Technologies

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Advanced IR emitters and sensors are under development for high detection probability, low false alarm rate, and identification capability of toxic gases. One of the most reliable techniques to identify the gas species is absorption spectroscopy, especially in the medium infrared spectral range, where most of existing toxic compounds exhibit their strongest rotovibrational absorption bands. Following the results obtained from simulations and analysis of expected absorption spectra, a compact nondispersive infrared multispectral system has been designed and developed for security applications. It utilizes a few square millimeters thermal source, a novel design multipass cell, and a smart architecture microbolometric sensor array coupled to a linear variable spectral filter to perform toxic gases detection and identification. This is done by means of differential absorption spectroscopic measurements in the spectral range of the midinfrared. Experimental tests for sensitivity and selectivity have been done with various chemical agents (CAs) gases and a multiplicity of vapour organic compounds (VOCs). Detection capability down to ppm has been demonstrated.

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Section: Discussionmentioning

confidence: 99%

Chemical Warfare Agents Analyzer Based on Low Cost, Room Temperature, and Infrared Microbolometer Smart Sensors

Corsi

Dundee

Laurenzi

et al. 2012

Advances in Optical Technologies

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“…Therefore, the algorithm can confidently be used to extrapolate ACLaS performance data to a wider range of threat molecules, providing reference absorption cross-section data are available. Table 3 shows calculated performance data for some selected chemicals, including the explosives nitroglycerine (NG), TATP and DADP 14 and the chemical warfare agents, Sarin (GB), Soman (GD) and Tabun (GA) 24,25,26 , using the experimentally demonstrated instrument SNR. Absorption cross-sections for TATP and Sarin are also indicated with black arrows on the right hand side of Figure 8 and are approximately 1 order of magnitude greater than those of narrow band absorbers such as N 2 O or CH 4 .…”

Section: Extrapolation To Further Threat Chemicalsmentioning

confidence: 99%

High sensitivity stand-off detection and quantification of chemical mixtures using an active coherent laser spectrometer (ACLaS)

Macleod

Weidmann

2016

SPIE Proceedings

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High sensitivity detection, identification and quantification of chemicals in a stand-off configuration is a highly sought after capability across the security and defense sector. Specific applications include assessing the presence of explosive related materials, poisonous or toxic chemical agents, and narcotics.Real world field deployment of an operational stand-off system is challenging due to stringent requirements: high detection sensitivity, stand-off ranges from centimeters to hundreds of meters, eye-safe invisible light, near real-time response and a wide chemical versatility encompassing both vapor and condensed phase chemicals. Additionally, field deployment requires a compact, rugged, power efficient, and cost-effective design.To address these demanding requirements, we have developed the concept of Active Coherent Laser Spectrometer (ACLaS), which can be also described as a middle infrared hyperspectral coherent lidar. Combined with robust spectral unmixing algorithms, inherited from retrievals of information from high-resolution spectral data generated by satellitebased spectrometers, ACLaS has been demonstrated to fulfil the above-mentioned needs.ACLaS prototypes have been so far developed using quantum cascade lasers (QCL) and interband cascade lasers (ICL) to exploit the fast frequency tuning capability of these solid state sources. Using distributed feedback (DFB) QCL, demonstration and performance analysis were carried out on narrow-band absorbing chemicals (N 2 O, H 2 O, H 2 O 2 , CH 4 , C 2 H 2 and C 2 H 6 ) at stand-off distances up to 50 m using realistic non cooperative targets such as wood, painted metal, and bricks. Using more widely tunable external cavity QCL, ACLaS has also been demonstrated on broadband absorbing chemicals (dichloroethane, HFC134a, ethylene glycol dinitrate and 4-nitroacetanilide solid) and on complex samples mixing narrow-band and broadband absorbers together in a realistic atmospheric background.

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“…This reference measurement is used to normalize subsequent measurements to obtain the relative transmittance spectra versus time. A graphical user interface was developed to control the instrument and a detection algorithm was developed that compares the measured transmittance with the entries in a spectral library [13][14][15]. Photograph of the tripod-mounted LaserWarn system during the testing.…”

Section: Demonstrationsmentioning

confidence: 99%

Detection of chemical clouds using widely tunable quantum cascade lasers

et al. 2015

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Widely tunable quantum cascade lasers (QCLs) spanning the long-wave infrared (LWIR) atmospheric transmission window and an HgCdTe detector were incorporated into a transceiver having a 50-mm-diameter transmit/receive aperture. The transceiver was used in combination with a 50-mm-diameter hollow retro-reflector for the open-path detection of chemical clouds. Two rapidly tunable external-cavity QCLs spanned the wavelength range of 7.5 to 12.8 m. Open-path transmission measurements were made over round-trip path-lengths of up to 562 meters. Freon-132a and other gases were sprayed into the beam path and the concentration-length (CL) product was measured as a function of time. The system exhibited a noise-equivalent concentration (NEC) of 3 ppb for Freon-132a given a round-trip path of 310 meters. Algorithms based on correlation methods were used to both identify the gases and determine their CLproducts as a function of time.

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Quantitative infrared spectra of vapor phase chemical agents

Cited by 31 publications

References 5 publications

Chemical Warfare Agents Analyzer Based on Low Cost, Room Temperature, and Infrared Microbolometer Smart Sensors

Chemical Warfare Agents Analyzer Based on Low Cost, Room Temperature, and Infrared Microbolometer Smart Sensors

High sensitivity stand-off detection and quantification of chemical mixtures using an active coherent laser spectrometer (ACLaS)

Detection of chemical clouds using widely tunable quantum cascade lasers

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