High-sensitivity explosives detection using dual-excitation-wavelength resonance-Raman detector

Yellampalle, Balakishore; McCormick, William; Wu, Haishan; Sluch, Mikhail; Martin, Robert B.; Ice, Robert; Lemoff, B. E.

doi:10.1117/12.2050441

Cited by 4 publications

(3 citation statements)

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“…The Raman features shift with excitation wavelength, but the broad fluorescence does not. In the deep UV, Yellampalle et al have adapted a similar scheme with the additional advantage that resonance Raman features also depend on the wavelength, resulting in substantial improvements to selectivity and reduction in false positives [115][116][117].…”

Section: Ramanmentioning

confidence: 99%

Advances in explosives analysis—part II: photon and neutron methods

et al. 2015

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The number and capability of explosives detection and analysis methods have increased dramatically since publication of the Analytical and Bioanalytical Chemistry special issue devoted to Explosives Analysis [Moore DS, Goodpaster JV, Anal Bioanal Chem 395:245-246, 2009]. Here we review and critically evaluate the latest (the past five years) important advances in explosives detection, with details of the improvements over previous methods, and suggest possible avenues towards further advances in, e.g., stand-off distance, detection limit, selectivity, and penetration through camouflage or packaging. The review consists of two parts. Part I discussed methods based on animals, chemicals (including colorimetry, molecularly imprinted polymers, electrochemistry, and immunochemistry), ions (both ion-mobility spectrometry and mass spectrometry), and mechanical devices. This part, Part II, will review methods based on photons, from very energetic photons including X-rays and gamma rays down to the terahertz range, and neutrons.

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Section: Ramanmentioning

confidence: 99%

Advances in explosives analysis—part II: photon and neutron methods

et al. 2015

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“…We have also used the DEW algorithm developed here to detect several explosives [15]. A library was created with fourteen different explosives or precursor materials.…”

Section: Other Explosive Detectionmentioning

confidence: 99%

Sensitive algorithm for multiple-excitation-wavelength resonance Raman spectroscopy

Yellampalle

McCormick

et al. 2014

SPIE Proceedings

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Raman spectroscopy is a widely used spectroscopic technique with a number of applications. During the past few years, we explored the use of simultaneous multiple-excitation-wavelengths (MEW) in resonance Raman spectroscopy. This approach takes advantage of Raman band intensity variations across the Resonance Raman spectra obtained from two or more excitation wavelengths. Amplitude variations occur between corresponding Raman bands in Resonance Raman spectra due to complex interplay of resonant enhancement, self-absorption and laser penetration depth. We have developed a very sensitive algorithm to estimate concentration of an analyte from spectra obtained using the MEW technique. The algorithm uses correlations and least-square minimization approach to calculate an estimate for the concentration. For two or more excitation wavelengths, measured spectra were stacked in a two dimensional matrix. In a simple realization of the algorithm, we approximated peaks in the ideal library spectra as triangles. In this work, we present the performance of the algorithm with measurements obtained from a dual-excitation-wavelength Resonance Raman sensor. The novel sensor, developed at WVHTCF, detects explosives from a standoff distance. The algorithm was able to detect explosives with very high sensitivity even at signal-to-noise ratios as low as ~1.6. Receiver operating characteristics calculated using the algorithm showed a clear benefit in using the dual-excitation-wavelength technique over single-excitation-wavelength techniques. Variants of the algorithm that add more weight to amplitude variation information showed improved specificity to closely resembling spectra.

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“…These spectral measurements were processed using an algorithm 17 to produce scores that help identify the explosive being measured. The algorithm, based on correlational least-squares, also takes advantage of the variation in Raman intensities between the two excitation wavelengths.…”

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confidence: 99%

Continuous-wave deep ultraviolet sources for resonance Raman explosive sensing

et al. 2015

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A promising approach to stand-off detection of explosive traces is using resonance Raman spectroscopy with Deepultraviolet (DUV) light. The DUV region offers two main advantages: strong explosive signatures due to resonant and λ -4 enhancement of Raman cross-section, and lack of fluorescence and solar background. For DUV Raman spectroscopy, continuous-wave (CW) or quasi-CW lasers are preferable to high peak powered pulsed lasers because Raman saturation phenomena and sample damage can be avoided. In this work we present a very compact DUV source that produces greater than 1 mw of CW optical power. The source has high optical-to-optical conversion efficiency, greater than 5 %, as it is based on second harmonic generation (SHG) of a blue/green laser source using a nonlinear crystal placed in an external resonant enhancement cavity. The laser system is extremely compact, lightweight, and can be battery powered. Using two such sources, one each at 236.5 nm and 257.5 nm, we are building a second generation explosive detection system called Dual-Excitation-Wavelength Resonance-Raman Detector (DEWRRED-II). The DEWRRED-II system also includes a compact dual-band high throughput DUV spectrometer, and a highly-sensitive detection algorithm. The DEWRRED technique exploits the DUV excitation wavelength dependence of Raman signal strength, arising from complex interplay of resonant enhancement, self-absorption and laser penetration depth. We show sensor measurements from explosives/precursor materials at different standoff distances.

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High-sensitivity explosives detection using dual-excitation-wavelength resonance-Raman detector

Cited by 4 publications

References 1 publication

Advances in explosives analysis—part II: photon and neutron methods

Advances in explosives analysis—part II: photon and neutron methods

Sensitive algorithm for multiple-excitation-wavelength resonance Raman spectroscopy

Continuous-wave deep ultraviolet sources for resonance Raman explosive sensing

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